doc: fix examples in repl.md

* Update an example according to an actual REPL session. * Replace an arrow function with a common function to hold `this`. PR-URL: #12684 Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: vsemozhetbyt

doc/api/repl.md

@@ -335,7 +335,7 @@ replServer.defineCommand('sayhello',{
 this.displayPrompt();
  }
 });
-replServer.defineCommand('saybye', () =>{
+replServer.defineCommand('saybye', functionsaybye(){
 console.log('Goodbye!');
 this.close();
 });
@@ -440,6 +440,8 @@ without passing any arguments (or by passing the `-i` argument):
 ```js
 $ node
 >consta= [1, 2, 3];
+undefined
+> a
 [ 1, 2, 3 ]
 >a.forEach((v) =>{
 ...console.log(v);