[ostree] Add some update instructions to the README

[Matthias Clasen <matthiasc src gnome org>]

commit 7a23350942d9856f906c8debb95ae342412e9cb6
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Feb 28 12:20:40 2012 -0500

    Add some update instructions to the README
    
    Everything is complicated for somebody who looks at this
    for the first time, so lets explain the basics.

 gnomeos/README-install.md |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)
---
diff --git a/gnomeos/README-install.md b/gnomeos/README-install.md
index 8c9f5c7..c66d3c7 100644
--- a/gnomeos/README-install.md
+++ b/gnomeos/README-install.md
@@ -46,3 +46,21 @@ Finally, you can start gdm:
 
 $ /usr/sbin/gdm
 
+Updating
+--------
+
+You need to pull the latest updates to your repos (assuming that
+you have your repos in /ostree)
+
+$ ostree-pull --repo=/ostree/repo origin gnomeos-3.4-i686-runtime
+$ ostree-pull --repo=/ostree/repo origin gnomeos-3.4-i686-devel
+
+And then you need to update your branches: to point to the new
+stuff. That is a little cumbersome, and the easiest is to use
+the gnomeos-update-branches script that comes with ostree. The
+script currently assumes that the repository is in the current
+directory.
+
+$ su -
+# cd /ostree
+# ~/src/ostree/gnomeos/yocto/gnomeos-update-branches.sh