sync: clarify Cond.Wait documentation
The previous wording was unclear and seemingly contradictory.
Change-Id: I0781dc4525948f4e8e5698271362a82387688f81
GitHub-Last-Rev:
c1e032fa9451dd50a69cf572cd80dcdbe6591d2e
GitHub-Pull-Request: golang/go#53516
Reviewed-on: https://go-review.googlesource.com/c/go/+/413774
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>