doc: update example in repl.md

Delete unused method call.

PR-URL: https://github.com/nodejs/node/pull/12685
Refs: https://github.com/nodejs/node/pull/6171
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

doc/api/repl.md

@@ -335,7 +335,6 @@ const replServer = repl.start({prompt: '> '});
 replServer.defineCommand('sayhello', {
   help: 'Say hello',
   action(name) {
-    this.lineParser.reset();
     this.bufferedCommand = '';
     console.log(`Hello, ${name}!`);
     this.displayPrompt();