Improve installation instructions for Go beginners

As a mentor at `exercism.io` I have to explain again and again how to install `golint`. Being new to Go they don't know where `golint` is installed and how to get it to work if they get the error message: `command not found`.

Change-Id: I44b7bedefe3a8c167ac5f956fde28fed6f7616fa
GitHub-Last-Rev: 41b2d10ab53ac583fde853363077fafd8d9e44c6
GitHub-Pull-Request: golang/lint#445
Reviewed-on: https://go-review.googlesource.com/c/lint/+/170278
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/README.md b/README.md
index b12ba63..487eba7 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,8 @@
 
     go get -u golang.org/x/lint/golint
 
+To find out where `golint` was installed you can run `go list -f {{.Target}} golang.org/x/lint/golint`. For `golint` to be used globally add that directory to the `$PATH` environment setting.
+
 ## Usage
 
 Invoke `golint` with one or more filenames, directories, or packages named