cmd/godoc: add x/website redirect

Add a redirect for the recently created x/website subrepository.

It's not yet included at https://golang.org/pkg/#subrepo because it's
in development. Once development reaches the point that x/website
is the canonical location of the golang.org server, we can consider
including x/website at https://golang.org/pkg/#subrepo (just like
x/blog, x/tour, x/build are already included there).

Updates golang/go#29206

Change-Id: I6889c1f5e40f11abca944b217a7354f76c08c8eb
Reviewed-on: https://go-review.googlesource.com/c/156337
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/godoc/x.go

@@ -47,7 +47,8 @@ var xMap = map[string]xRepo{
 	"time":       {"https://go.googlesource.com/time", "git"},
 	"tools":      {"https://go.googlesource.com/tools", "git"},
 	"tour":       {"https://go.googlesource.com/tour", "git"},
-	"vgo":        {"https://go.googlesource.com/vgo", "git"}, // Not included at https://golang.org/pkg/#subrepo.
+	"vgo":        {"https://go.googlesource.com/vgo", "git"},     // Not included at https://golang.org/pkg/#subrepo.
+	"website":    {"https://go.googlesource.com/website", "git"}, // Not included at https://golang.org/pkg/#subrepo.
 }
 
 func init() {