Remove duplicate words in comments (#4986)

modules/caddyhttp/reverseproxy/reverseproxy.go

@@ -1360,7 +1360,7 @@ var bufPool = sync.Pool{
 }
 
 // handleResponseContext carries some contextual information about the
-// the current proxy handling.
+// current proxy handling.
 type handleResponseContext struct {
 	// handler is the active proxy handler instance, so that
 	// routes like copy_response may inherit some config