Document that Go source files live in google/go-genproto (#59)
Document that Go source files live in google/go-genproto (#59)

* Document that Go source files live in google/go-genproto

* Address PR comments

shinfan/googleapis,pongad/googleapis,garrettjonesgoogle/googleapis,ethanbao/googleapis,googleapis/googleapis,googleapis/googleapis,landrito/googleapis,speedycontrol/googleapis,fuchsia-mirror/third_party-googleapis