api/register-queue: Recommend using zuliprc.

Recommend using a zuliprc file instead of hardcoding the API
credentials in a config object.

templates/zerver/api/register-queue.md

@@ -60,21 +60,17 @@ More examples and documentation can be found [here](https://github.com/zulip/zul
 ```js
 const zulip = require('zulip-js');
 
+// Download zuliprc-dev from your dev server
 const config = {
-  username: 'othello-bot@example.com',
-  apiKey: 'a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5',
-  realm: '{{ api_url }}'
+    zuliprc: 'zuliprc-dev',
 };
 
-const client = zulip(config);
-
+zulip(config).then((client) => {
     // Register a queue
     const params = {
         event_types: ['message']
     };
-
-client.queues.register(params).then(res => {
-    console.log(res);
+    client.queues.register(params).then(console.log);
 });
 
 ```