errors: clarify Join documentation
The previous documentation used a double-negative in describing Join behavior; this use of language could be confusing.
This update removes the double-negative.
Change-Id: If13e88682e865314a556e7d381143a97fa5486d9
GitHub-Last-Rev:
92b3f88a5d49229e71adafcfa7b1d01dcb7646f3
GitHub-Pull-Request: golang/go#59082
Reviewed-on: https://go-review.googlesource.com/c/go/+/477095
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>