readme: document golang v1.7 requiremend
@@ -26,7 +26,7 @@ instructions](https://packagecloud.io/travisci/worker/install).
### from source
1. clone this down
-1. install [Go](http://golang.org)
+1. install [Go](http://golang.org) `v1.7+`
1. install [gvt](https://github.com/FiloSottile/gvt):
* `go get -u github.com/FiloSottile/gvt`
1. install [gometalinter](https://github.com/alecthomas/gometalinter):
