reflect: make linkable cross-references in documentation
This makes it easier to click around in documentation on pkg.go.dev.
Change-Id: Idc67c312bc72c612e660607e5400b43ecc110bc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/514895
Run-TryBot: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@google.com> Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>