Update README.md

to get the source right

README.md

@@ -65,7 +65,7 @@ There is currently only one bundle of `go-libp2p`, this package. This bundle is
 ### Install
 
 ```bash
-> go get -d github.com/libp2p/go-libp2p/...
+> go get -u -d github.com/libp2p/go-libp2p/...
 > cd $GOPATH/src/github.com/libp2p/go-libp2p
 > make
 > make deps