doc: clean up isDead() example

This commit removes extra whitespace and some awkward text
containing typos from the cluster worker.isDead() code
sample.

PR-URL: #28421
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/cluster.md

@@ -401,19 +401,14 @@ if (cluster.isMaster) {
   cluster.on('exit', (worker, code, signal) => {
     console.log('worker is dead:', worker.isDead());
   });
-
 } else {
-  // Workers can share any TCP connection
-  // In this case it is an HTTP server
+  // Workers can share any TCP connection. In this case, it is an HTTP server.
   http.createServer((req, res) => {
     res.writeHead(200);
     res.end(`Current process\n ${process.pid}`);
     process.kill(process.pid);
   }).listen(8000);
-
-  // Make http://localhost:8000 to ckeck isDead method.
 }
-
 ```
 
 ### worker.kill([signal='SIGTERM'])