CONTRIBUTING.md: remove note about not accepting Pull Requests

Updates golang/go#24185

Change-Id: Ia2de9218885e0cfeaec79ed7417475230b063df0
Reviewed-on: https://go-review.googlesource.com/100692Reviewed-by: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

CONTRIBUTING.md

@@ -4,7 +4,6 @@ Go is an open source project.
 
 It is the work of hundreds of contributors. We appreciate your help!
 
-
 ## Filing issues
 
 When [filing an issue](https://golang.org/issue/new), make sure to answer these five questions:
@@ -23,9 +22,5 @@ The gophers there will answer or ask you to file an issue if you've tripped over
 Please read the [Contribution Guidelines](https://golang.org/doc/contribute.html)
 before sending patches.
 
-**We do not accept GitHub pull requests**
-(we use [Gerrit](https://code.google.com/p/gerrit/) instead for code review).
-
 Unless otherwise noted, the Go source files are distributed under
 the BSD-style license found in the LICENSE file.
-