cmd/go: update pkgsite doc command to v0.0.0-20251223195805-1a3bd3c788fe

cmd/go: update pkgsite doc command to v0.0.0-20251223195805-1a3bd3c788fe

This pulls in a version of the pkgsite doc command that includes CL
729900 which adds support for showing documentation for some of our
experiments

Change-Id: I52aebf06521adc114aa90f99f515f2746a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/732400
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Sean Liao <sean@liao.dev>
Auto-Submit: Michael Matloob <matloob@golang.org>
Reviewed-by: Michael Matloob <matloob@google.com>