Fix validation in platform-overview
Fix validation in platform-demos
Add index and Makefile to devel-guide
Move integration guide to devel-guide
Add another section to devel-guide index

The first section of the devel-guide should be a simple walkthrough
example of an application, the second section which should be stuff to
expand on writing an application. Third section, at some point in the
future should be advanced stuff.
Add 'Write a GNOME Shell extension' series
Update docs on adding help