The receiver was renamed 6 years ago in https://golang.org/cl/5674065
but the docs weren't updated to match.

Change-Id: I5e72cedc0e0f067382545d272f48a9c7dfb5a9b7
Reviewed-on: https://go-review.googlesource.com/104116Reviewed-by: Ian Lance Taylor <iant@golang.org>