Add contribution guidelines (#360)
Add contribution guidelines (#360)

Since the number of actual and possible developers is exanding, it's
probably time to describe the contribution guidelines more explicitly.
Here's an initial version based on our existing documentation, primed
with some friction points encountered during code review so far.
cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra