old install instructions for grpcurl

[felixvonberlin]

Hi everyone,
I've just discovered that when you want to install grpcurl like it is described in consensus/api/README.md you get an error saying that the syntax of the go management tool has changed.
The old syntax looks like this (copied from the readme):

go get github.com/fullstorydev/grpcurl
go install github.com/fullstorydev/grpcurl/cmd/grpcurl

But to get it working, now I've used:

go install github.com/fullstorydev/grpcurl@latest
go install github.com/fullstorydev/grpcurl/cmd/grpcurl@latest

It is really not urgent, but it's nice to know, I think.