Add contributing file
Add contributing file

Includes instructions on packaging a new release version

makingspace/liftoff,fousa/liftoff,makingspace/liftoff,fhchina/liftoff,IntrepidPursuits/homebrew-liftoff,makingspace/liftoff,liftoffcli/liftoff,fousa/liftoff,IntrepidPursuits/homebrew-liftoff,liftoffcli/liftoff,fhchina/liftoff,liftoffcli/liftoff,fhchina/liftoff,fousa/liftoff,IntrepidPursuits/homebrew-liftoff