Update README with contributing conventions.
Update README with contributing conventions.

[#108021626]

Signed-off-by: Zak Auerbach <84a275e6a279738f2aa78daf0002615dee69cc28@pivotal.io>

matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests,matt-royal/cf-acceptance-tests