doc: fix repl defineCommand example

Fixes: #7357
PR-URL: #7365
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: akki

doc/api/repl.md

@@ -312,12 +312,12 @@ replServer.defineCommand('sayhello', {
   action: function(name) {
     this.lineParser.reset();
     this.bufferedCommand = '';
-    this.write(`Hello, ${name}!\n`);
+    console.log(`Hello, ${name}!`);
     this.displayPrompt();
   }
 });
 replServer.defineCommand('saybye', function() {
-  this.write('Goodbye!\n');
+  console.log('Goodbye!');
   this.close();
 });
 ```