Add release note.
Add release note.

jhamm/FsCheck,paulyoung/FsCheck,fsharp/FsCheck,sideeffffect/FsCheck,ErikSchierboom/FsCheck,paulyoung/FsCheck,cloudRoutine/FsCheck,forki/FsCheck,fscheck/FsCheck,ploeh/FsCheck,forki/FsCheck,cloudRoutine/FsCheck,fscheck/FsCheck