Not the right approach.
««« original CL description
go.tools/godoc: reverse reversed redirects
Make godoc work again for go spec and memory model doc.
TBR=rsc
CC=golang-dev
https://golang.org/cl/14368043
»»»
R=gri
CC=golang-dev
https://golang.org/cl/14370043
It was not enough to make /ref/spec work (which it now does),
because some of the docs on golang.org (in particular golang.org/doc)
are pulled from tip, and tip links to /doc/spec now.
Make those "too new" links work by redirecting /doc/spec
back to /ref/spec for now.
TBR=adg
CC=golang-dev
https://golang.org/cl/14348043