fmt: document nil receiver handling for GoStringer
Fixes #70305
Change-Id: I8ae4e6dae3327a54039d470c8c8545e2cc6de98f
Reviewed-on: https://go-review.googlesource.com/c/go/+/627495 Reviewed-by: Rob Pike <r@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>