errors: improve the godoc for Join and Unwrap
Document that errors returned by Join always implement Unwrap []error.
Explicitly state that Unwrap does not unwrap errors
with an Unwrap() []error method.
Change-Id: Id610345dcf43ca54a9dde157e56c5815c5112073
GitHub-Last-Rev:
7a0ec450bd0b2b38eecb5b94eaec485f4a6debbd
GitHub-Pull-Request: golang/go#59301
Reviewed-on: https://go-review.googlesource.com/c/go/+/480021
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
Auto-Submit: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>