cmd/coordinator: generate table of builders

To replace the always-out-of-date wiki.

Change-Id: I63d56d4bcf9252e56c833eaa15656b0321ac91dc
Reviewed-on: https://go-review.googlesource.com/9571
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/cmd/coordinator/coordinator.go b/cmd/coordinator/coordinator.go
index 9c1d7f8..b6cd412 100644
--- a/cmd/coordinator/coordinator.go
+++ b/cmd/coordinator/coordinator.go
@@ -258,11 +258,12 @@
 	}
 
 	http.HandleFunc("/", handleStatus)
-	http.HandleFunc("/try", handleTryStatus)
-	http.HandleFunc("/logs", handleLogs)
 	http.HandleFunc("/debug/goroutines", handleDebugGoroutines)
+	http.HandleFunc("/builders", handleBuilders)
+	http.HandleFunc("/logs", handleLogs)
 	http.HandleFunc("/reverse", handleReverse)
 	http.HandleFunc("/style.css", handleStyleCSS)
+	http.HandleFunc("/try", handleTryStatus)
 	go func() {
 		if *mode == "dev" {
 			return