[gnome-builder] doc: add basic flatpak bundle export docs

[Christian Hergert <chergert src gnome org>]

commit 705651118f6cfd32942ce6579ce06930f4f878de
Author: Christian Hergert <chergert redhat com>
Date:   Sat Sep 2 23:27:26 2017 -0700

    doc: add basic flatpak bundle export docs

 doc/figures/export.png         |  Bin 0 -> 219391 bytes
 doc/figures/flatpak-bundle.png |  Bin 0 -> 114917 bytes
 doc/projects/sharing.rst       |   19 +++++++++++++++++++
 3 files changed, 19 insertions(+), 0 deletions(-)
---
diff --git a/doc/figures/export.png b/doc/figures/export.png
new file mode 100644
index 0000000..9c86951
Binary files /dev/null and b/doc/figures/export.png differ
diff --git a/doc/figures/flatpak-bundle.png b/doc/figures/flatpak-bundle.png
new file mode 100644
index 0000000..aa8d1a3
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diff --git a/doc/projects/sharing.rst b/doc/projects/sharing.rst
index cff9367..442d6c5 100644
--- a/doc/projects/sharing.rst
+++ b/doc/projects/sharing.rst
@@ -1,3 +1,22 @@
 ####################
 Sharing your Project
 ####################
+
+By default the application templates in Builder will use Flatpak.
+This makes it easy to bundle your project and share it with a friend.
+
+When using Flatpak, you can click the "Export Bundle" button in the build popover.
+
+.. image:: ../figures/export.png
+   :width: 1075 px
+   :align: center
+
+At this point Builder will build and install your project using the Flatpak build tooling.
+After it completes, Files will open the build directory to reveal your new flatpak.
+This can be opened with Software to install on your or a friends system.
+
+.. image:: ../figures/flatpak-bundle.png
+   :width: 724 px
+   :align: center
+
+