Adjust LAYOUT to correctly state format of README.rst

In ~November 2009, we created README.mkd.

Later, we converted it to reStructuredText and renamed it.
No one fixed LAYOUT... until now!
Remark on origin of vendor/ trick
Encourage harder people to read README
Explain that this is Django-y
Explain other bits of Django we use
Merge pull request #154 from paulproteus/feature/longer-layout-file

Explain the LAYOUT of the code better