Update the lint version requirements in README.md

Per the discussion in #400, lint is supported under the same policy as Go itself, and is not supported from a particular version any more.

Change-Id: I97c9b284fb725b19143462ae22c525b22267257d
GitHub-Last-Rev: 73cd8baafc34121a88c420628e24900221a170d7
GitHub-Pull-Request: golang/lint#401
Reviewed-on: https://go-review.googlesource.com/110115
Reviewed-by: Andrew Bonventre <andybons@golang.org>
diff --git a/README.md b/README.md
index d622617..fb61933 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,8 @@
 
 ## Installation
 
-Golint requires Go 1.6 or later.
+Golint requires a
+[supported release of Go](https://golang.org/doc/devel/release.html#policy).
 
     go get -u golang.org/x/lint/golint