[gnome-builder] doc: add blurb about --standalone option

[Christian Hergert <chergert src gnome org>]

commit 3f8cf7a177f4552f90535bf1db7422c0270f7b87
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jul 5 01:50:11 2017 -0700

    doc: add blurb about --standalone option

 doc/contributing/code.rst |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/doc/contributing/code.rst b/doc/contributing/code.rst
index 2d93273..3813b16 100644
--- a/doc/contributing/code.rst
+++ b/doc/contributing/code.rst
@@ -30,6 +30,13 @@ There are many `existing plugins`_ already.
 You might want to contribute to an existing one that does not yet serve your needs well.
 Or maybe you want to :ref:`create a new plugin<creating_plugins>` that integrates a feature missing from 
Builder.
 
+Running
+-------
+
+You might find yourself running Builder from Builder.
+By default, that will activate and bring-forward your previous instance of Builder.
+If you run Builder from the command-line with ``--standalone``, it will not communicate with another 
instance of Builder.
+
 .. _libide: https://git.gnome.org//browse/gnome-builder/tree/libide/
 .. _git: https://git.gnome.org//browse/gnome-builder/tree/plugins/git/
 .. _`existing plugins`: https://git.gnome.org//browse/gnome-builder/tree/plugins/