[gnome-builder] doc: add editor blurb

[Christian Hergert <chergert src gnome org>]

commit b2330a261fe91487f1961cf1fb1f470b55f27b14
Author: Christian Hergert <chergert redhat com>
Date:   Thu Sep 7 01:11:41 2017 -0700

    doc: add editor blurb

 doc/exploring.rst      |   11 +++++++++++
 doc/figures/editor.png |  Bin 0 -> 371788 bytes
 2 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/doc/exploring.rst b/doc/exploring.rst
index aa819e4..871ef48 100644
--- a/doc/exploring.rst
+++ b/doc/exploring.rst
@@ -122,6 +122,17 @@ Editor
 When Builder opens your project, it will place you in the editor perspective.
 This is where you develop your project.
 
+.. image:: figures/editor.png
+   :width: 1415 px
+   :align: center
+
+Along the left is the project sidebar. It contains the project tre, list of
+open documents, todo items, and build errors. Generally, it contains the
+"source" or things to work on in your project.
+
+Along the bottom is the utilities panel. Here you will find things like the
+debugger, terminal, build, and application console.
+
 Autocompletion
 --------------
 
diff --git a/doc/figures/editor.png b/doc/figures/editor.png
new file mode 100644
index 0000000..9a30711
Binary files /dev/null and b/doc/figures/editor.png differ