Fix pluralization for subject(s)

- Change condition in two-custom-written-middlewares.js from
  MessageCount <= 1 to MessageCount === 1 so "subject" is used only
  when there is exactly one item (zero now uses "subjects").

Author: Iswanna

middleware-exercise/two-custom-written-middlewares.js

@@ -64,7 +64,7 @@ app.post("/", usernameMiddleware, arrayMiddleware, (req, res) => {
 
   const messageJoined = req.body.join(",");
 
-  const word = MessageCount <= 1 ? "subject" : "subjects";
+  const word = MessageCount === 1 ? "subject" : "subjects";
 
   if (MessageCount > 0) {
     res.send(