crypto/ssh: fix the links to the SSH protocol documents

Minor change - updated the links to the ssh PROTOCOL.* docs.
Currently the [PROTOCOL...] links in References on top of
https://godoc.org/golang.org/x/crypto/ssh and
https://godoc.org/golang.org/x/crypto/ssh/agent
take you to the top-level directory list on
http://cvsweb.openbsd.org/cgi-bin/cvsweb/
instead of directly to the respective document pages.

Change-Id: Ifd3f0bc2ef393ab02f023c13b93340fdb0a05af3
Reviewed-on: https://go-review.googlesource.com/8963
Reviewed-by: Adam Langley <agl@golang.org>
2 files changed