io/fs,path/filepath: fix typo in SkipAll/SkipDir doc
Also make the reference into a doc link.
Change-Id: Ib112307a65b65c8f963abf60aa92cb1942de940c
Reviewed-on: https://go-review.googlesource.com/c/go/+/554295 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>