go get fails for xxhash/v2

[sepastian]

I am following the guide for client_golang: https://prometheus.io/docs/guides/go-application/

Installing promhttp with go get fails because of an invalid dependency on xxhash/v2.

$ go get github.com/prometheus/client_golang/prometheus/promhttp
package github.com/cespare/xxhash/v2: cannot find package "github.com/cespare/xxhash/v2" in any of:
	/home/sebastian/.asdf/installs/golang/1.10/go/src/github.com/cespare/xxhash/v2 (from $GOROOT)
	/home/sebastian/Code/sipts/worker-base/src/github.com/cespare/xxhash/v2 (from $GOPATH)

$ go version
go version go1.10 linux/amd64

The URL https://github.com/cespare/xxhash/v2 is invalid; should this read https://github.com/cespare/xxhash/tree/v2 instead?

[beorn7]

This is a change introduced by go modules. To make it work with older Go versions, those got patched. You need to run go go 1.10.3+.

I'll add that to the README.md.

[beorn7]

Now addressed in README.md.

[sepastian]

I tried with go 1.13.1 yesterday, it works there. Thanks!