A reminder about the default git branch -- it is the development version

Hi everyone!

I've seen a lot of folks "using ansible in production" using the
development branch, which is the default branch of github.

While I am very thankful for the high quality of testing this produces
(very very very thankful and I can't say it enough), it's also
something you should be cautious of doing, as the purpose of the
development branch is to develop the next version of ansible.

We need a mix of folks willing to constantly use the latest and test
the latest, but please do remember that the stable version is on the
"release-XX" branch in github, and is not what you get when you do a
top level checkout.

--Michael