ref(docs): move "get the source" header to the including document

Author: mboersma

docs/_includes/_get-the-source.rst

@@ -1,6 +1,3 @@
-Get the Source
---------------
-
 The `source code`_ for Deis must be on your workstation to run the commands in
 this documentation. Download an archive file from the `releases page`_, or use
 ``git`` to clone the repository:

docs/installing_deis/quick-start.rst

@@ -9,7 +9,9 @@ These steps will help you provision a Deis cluster.
 
 .. _get_the_source:
 
-.. "Get the Source" section
+Get the Source
+--------------
+
 .. include:: ../_includes/_get-the-source.rst