internal/frontend: add /search-stats endpoint

A /search-stats endpoint is added so that stats for the search handler
can be viewed.

For golang/go#44142

Change-Id: I7f17496348b78610ce82687ec2713a2e9dfbfdf6
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/341491
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/internal/frontend/server.go b/internal/frontend/server.go
index 8168be1..96c83e3 100644
--- a/internal/frontend/server.go
+++ b/internal/frontend/server.go
@@ -151,6 +151,8 @@
 	if s.serveStats {
 		handle("/detail-stats/",
 			middleware.Stats()(http.StripPrefix("/detail-stats", s.errorHandler(s.serveDetails))))
+		handle("/search-stats/",
+			middleware.Stats()(http.StripPrefix("/search-stats", s.errorHandler(s.serveSearch))))
 	}
 	handle("/robots.txt", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "text/plain; charset=utf-8")