[ostree] README: Attempt to flesh out more, start moving docs from wiki

[Colin Walters <walters src gnome org>]

commit cd6eac2ce9abaad6ae070b8fa981dfa09de26359
Author: Colin Walters <walters verbum org>
Date:   Tue Jul 28 18:38:47 2015 -0400

    README: Attempt to flesh out more, start moving docs from wiki
    
    I'd like to migrate content from the GNOME wiki, as frankly the wiki
    is crap.  Markdown in git is better in every way.
    
    Start by fleshing out the README.md to be more useful.

 CONTRIBUTING.md            |  121 ++++++++++++++++++++++++++++++
 README.md                  |  177 +++++++++++++++-----------------------------
 docs-md/atomic-upgrades.md |   12 +++
 3 files changed, 193 insertions(+), 117 deletions(-)
---
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..4458256
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,121 @@
+Submitting patches
+------------------
+
+You can:
+
+ 1. Send mail to ostree-list gnome org, with the patch attached
+ 1. Submit a pull request against https://github.com/GNOME/ostree
+ 1. Attach them to https://bugzilla.gnome.org/
+
+Please look at "git log" and match the commit log style.
+
+Running the test suite
+----------------------
+
+Currently, ostree uses https://wiki.gnome.org/GnomeGoals/InstalledTests
+To run just ostree's tests:
+
+    ./configure ... --enable-installed-tests
+    gnome-desktop-testing-runner -p 0 ostree/
+
+Also, there is a regular:
+
+    make check
+
+That runs a different set of tests.
+
+Coding style
+------------
+
+Indentation is GNU.  Files should start with the appropriate mode lines.
+
+Use GCC `__attribute__((cleanup))` wherever possible.  If interacting
+with a third party library, try defining local cleanup macros.
+
+Use GError and GCancellable where appropriate.
+
+Prefer returning `gboolean` to signal success/failure, and have output
+values as parameters.
+
+Prefer linear control flow inside functions (aside from standard
+loops).  In other words, avoid "early exits" or use of `goto` besides
+`goto out;`.
+
+This is an example of an "early exit":
+
+    static gboolean
+    myfunc (...)
+    {
+        gboolean ret = FALSE;
+    
+        /* some code */
+    
+        /* some more code */
+    
+        if (condition)
+          return FALSE;
+    
+        /* some more code */
+    
+        ret = TRUE;
+      out:
+        return ret;
+    }
+
+If you must shortcut, use:
+
+    if (condition)
+      {
+        ret = TRUE;
+        goto out;
+      }
+
+A consequence of this restriction is that you are encouraged to avoid
+deep nesting of loops or conditionals.  Create internal static helper
+functions, particularly inside loops.  For example, rather than:
+
+    while (condition)
+      {
+        /* some code */
+        if (condition)
+          {
+             for (i = 0; i < somevalue; i++)
+               {
+                  if (condition)
+                    {
+                      /* deeply nested code */
+                    }
+    
+                    /* more nested code */
+               }
+          }
+      }
+
+Instead do this:
+    
+    static gboolean
+    helperfunc (..., GError **error)
+    {
+      if (condition)
+       {
+         /* deeply nested code */
+       }
+    
+      /* more nested code */
+    
+      return ret;
+    }
+    
+    while (condition)
+      {
+        /* some code */
+        if (!condition)
+          continue;
+    
+        for (i = 0; i < somevalue; i++)
+          {
+            if (!helperfunc (..., i, error))
+              goto out;
+          }
+      }
+    
diff --git a/README.md b/README.md
index d4b4c42..ac070da 100644
--- a/README.md
+++ b/README.md
@@ -1,132 +1,75 @@
-OSTree is a tool for managing bootable, immutable, versioned
-filesystem trees. While it takes over some of the roles of traditional
-"package managers" like dpkg and rpm, it is not a package system; nor
-is it a tool for managing full disk images. Instead, it sits between
-those levels, offering a blend of the advantages (and disadvantages)
-of both.
+OSTree
+======
 
-For more information, see:
+OSTree is a tool that combines a "git-like" model for committing and
+downloading bootable filesystem trees, along with a layer for
+deploying them and managing the bootloader configuration.
 
-https://live.gnome.org/Projects/OSTree
+Traditional package managers (dpkg/rpm) build filesystem trees on the
+client side.  In contrast, the primary focus of OSTree is on
+replicating trees composed on a server.
 
-Submitting patches
-------------------
+**Features:**
+
+ - Atomic upgrades and rollback
+ - GPG signatures and "pinned TLS" support
+ - Support for parallel installing more than just 2 bootable roots
+ - Binary history on the server side
+ - Introspectable shared library API for build and deployment systems
+
+Projects using OSTree
+---------------------
+
+[rpm-ostree](https://github.com/projectatomic/rpm-ostree) is a tool
+that uses OSTree as a shared library, and supports committing RPMs
+into an OSTree repository, and deploying them on the client.
 
-You can:
+[Project Atomic](http://www.projectatomic.io/) uses rpm-ostree
+to provide a minimal host for Docker formatted Linux containers.
 
- 1. Send mail to ostree-list gnome org, with the patch attached
- 1. Submit a pull request against https://github.com/GNOME/ostree
- 1. Attach them to https://bugzilla.gnome.org/
+[xdg-app](https://github.com/alexlarsson/xdg-app) uses OSTree 
+for desktop application containers.
 
-Please look at "git log" and match the commit log style.
+[GNOME Continuous](https://wiki.gnome.org/Projects/GnomeContinuous) is
+a custom build system designed for OSTree, using
+[OpenEmbedded](http://www.openembedded.org/wiki/Main_Page) in concert
+with a custom build system to do continuous delivery from hundreds of
+git repositories.
 
-Running the test suite
-----------------------
+Building
+--------
 
-Currently, ostree uses https://wiki.gnome.org/GnomeGoals/InstalledTests
-To run just ostree's tests:
+Releases are available as GPG signed git tags, and most recent
+versions support extended validation using
+[git-evtag](https://github.com/cgwalters/git-evtag).
 
-    ./configure ... --enable-installed-tests
-    gnome-desktop-testing-runner -p 0 ostree/
+However, in order to build from a git clone, you must update the
+submodules.  If you're packaging OSTree and want a tarball, I
+recommend using a "recursive git archive" script.  There are several
+available online; [this
+code](https://git.gnome.org/browse/ostree/tree/packaging/Makefile.dist-packaging#n11)
+in OSTree is an example.
 
-Also, there is a regular:
+Once you have a git clone or recursive archive, building is the
+same as almost every autotools project:
+
+```
+env NOCONFIGURE=1 ./autogen.sh
+./configure --prefix=...
+make
+make install DESTDIR=/path/to/dest
+```
+
+More documentation
+------------------
 
-    make check
+Some more information is available on the old wiki page:
+https://wiki.gnome.org/Projects/OSTree
 
-That runs a different set of tests.
+The intent is for that wiki page content to be migrated into Markdown
+in this git repository.
 
-Coding style
+Contributing
 ------------
 
-Indentation is GNU.  Files should start with the appropriate mode lines.
-
-Use GCC `__attribute__((cleanup))` wherever possible.  If interacting
-with a third party library, try defining local cleanup macros.
-
-Use GError and GCancellable where appropriate.
-
-Prefer returning `gboolean` to signal success/failure, and have output
-values as parameters.
-
-Prefer linear control flow inside functions (aside from standard
-loops).  In other words, avoid "early exits" or use of `goto` besides
-`goto out;`.
-
-This is an example of an "early exit":
-
-    static gboolean
-    myfunc (...)
-    {
-        gboolean ret = FALSE;
-    
-        /* some code */
-    
-        /* some more code */
-    
-        if (condition)
-          return FALSE;
-    
-        /* some more code */
-    
-        ret = TRUE;
-      out:
-        return ret;
-    }
-
-If you must shortcut, use:
-
-    if (condition)
-      {
-        ret = TRUE;
-        goto out;
-      }
-
-A consequence of this restriction is that you are encouraged to avoid
-deep nesting of loops or conditionals.  Create internal static helper
-functions, particularly inside loops.  For example, rather than:
-
-    while (condition)
-      {
-        /* some code */
-        if (condition)
-          {
-             for (i = 0; i < somevalue; i++)
-               {
-                  if (condition)
-                    {
-                      /* deeply nested code */
-                    }
-    
-                    /* more nested code */
-               }
-          }
-      }
-
-Instead do this:
-    
-    static gboolean
-    helperfunc (..., GError **error)
-    {
-      if (condition)
-       {
-         /* deeply nested code */
-       }
-    
-      /* more nested code */
-    
-      return ret;
-    }
-    
-    while (condition)
-      {
-        /* some code */
-        if (!condition)
-          continue;
-    
-        for (i = 0; i < somevalue; i++)
-          {
-            if (!helperfunc (..., i, error))
-              goto out;
-          }
-      }
-    
+See [Contributing](CONTRIBUTING.md).
diff --git a/docs-md/atomic-upgrades.md b/docs-md/atomic-upgrades.md
new file mode 100644
index 0000000..76cd025
--- /dev/null
+++ b/docs-md/atomic-upgrades.md
@@ -0,0 +1,12 @@
+Atomic upgrades and rollback
+----------------------------
+
+Traditional package managers operate "live" on the running system.
+This means it's possible for interrupted updates to result in a
+half-updated system.  This model also makes it significantly harder to
+support rollbacks when updates fail.
+
+In contrast, OSTree always creates a *new* root whenever it's
+performing an update.  This new root shares storage via hardlinks with
+the current system.  Upon success, the bootloader configuration will
+be updated.