conf: Change workflow
conf: Change workflow

Version 0.9 changed the development model to fast-forwarding on a single
`develop` branch.  The next version will be developed on the `master`
branch.

The workflow is now:
 - branch off master
 - develop on another branch
 - once done, clean up and rebase on master
 - squash/fast-forward merge on master

Synss/python-mbedtls,Synss/python-mbedtls