spec: explain eval order of binary operator examples with comments
Fixes #63525.
Change-Id: Ie9aa4dd47c025cd593e576c6e8de1774e1d1e302
Reviewed-on: https://go-review.googlesource.com/c/go/+/535775 Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Bypass: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>