io: clarify SeekEnd offset value
fixes #53474
Change-Id: I14c3dc800dc27233630a54592328bb0df1bbaa5d
GitHub-Last-Rev:
46f93cfbd41c1b3274b570744f18d08e7759eb1e
GitHub-Pull-Request: golang/go#53505
Reviewed-on: https://go-review.googlesource.com/c/go/+/413614
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>