.: add codereview.cfg

This makes git-codereview review issue references
to refer to the main Go repo.

Change-Id: I17003885f15358f776a475a76a31dac179de9676
Reviewed-on: https://go-review.googlesource.com/33908
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed