docs: Add GitHub contributions file
docs: Add GitHub contributions file

This commit adds the HACKING file with GitHub specific formatting and an
extra section on reporting issues to bugzilla.

arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee,arfbtwn/banshee