Add RELEASE_PROCESS document (#1217)
Add RELEASE_PROCESS document (#1217)

Checklist on how to do pony releases.
Theodus/ponyc,boemmels/ponyc,kulibali/ponyc,Perelandric/ponyc,Perelandric/ponyc,sgebbie/ponyc,mkfifo/ponyc,boemmels/ponyc,cquinn/ponyc,jupvfranco/ponyc,mkfifo/ponyc,sgebbie/ponyc,jupvfranco/ponyc,malthe/ponyc,CausalityLtd/ponyc,jemc/ponyc,Praetonus/ponyc,cquinn/ponyc,jemc/ponyc,Praetonus/ponyc,Praetonus/ponyc,mkfifo/ponyc,sgebbie/ponyc,dipinhora/ponyc,ponylang/ponyc,Theodus/ponyc,boemmels/ponyc,cquinn/ponyc,ponylang/ponyc,Theodus/ponyc,dipinhora/ponyc,CausalityLtd/ponyc,Perelandric/ponyc,kulibali/ponyc,sgebbie/ponyc,jupvfranco/ponyc,kulibali/ponyc,boemmels/ponyc,boemmels/ponyc,sgebbie/ponyc,malthe/ponyc,Theodus/ponyc,Perelandric/ponyc,jemc/ponyc,malthe/ponyc,mkfifo/ponyc,CausalityLtd/ponyc,kulibali/ponyc,Praetonus/ponyc,jupvfranco/ponyc,cquinn/ponyc,malthe/ponyc,mkfifo/ponyc,ponylang/ponyc,Theodus/ponyc,Perelandric/ponyc,dipinhora/ponyc,jupvfranco/ponyc