README: add pointer to http://kentonv.github.io/capnproto/
README: add pointer to http://kentonv.github.io/capnproto/

hodduc/go-capnproto2,zombiezen/go-capnproto2,hodduc/go-capnproto2,tpukep/caps,zombiezen/go-capnproto,zombiezen/go-capnproto,zombiezen/go-capnproto2