Feat: add new Markdown parser (#39800)

and change all the challenges to new `md` format.

curriculum/challenges/english/06-quality-assurance/advanced-node-and-express/handle-a-disconnect.md

@@ -5,13 +5,11 @@ challengeType: 2
 forumTopicId: 301552
 ---
 
-## Description
-
-<section id='description'>
+# --description--
 
 You may notice that up to now you have only been increasing the user count. Handling a user disconnecting is just as easy as handling the initial connect, except you have to listen for it on each socket instead of on the whole server.
 
-To do this, add another listener inside the existing <code>'connect'</code> listener that listens for <code>'disconnect'</code> on the socket with no data passed through. You can test this functionality by just logging that a user has disconnected to the console.
+To do this, add another listener inside the existing `'connect'` listener that listens for `'disconnect'` on the socket with no data passed through. You can test this functionality by just logging that a user has disconnected to the console.
 
 ```js
 socket.on('disconnect', () => {
@@ -21,41 +19,47 @@ socket.on('disconnect', () => {
 
 To make sure clients continuously have the updated count of current users, you should decrease the currentUsers by 1 when the disconnect happens then emit the 'user count' event with the updated count!
 
-<strong>Note:</strong> Just like <code>'disconnect'</code>, all other events that a socket can emit to the server should be handled within the connecting listener where we have 'socket' defined.
+**Note:** Just like `'disconnect'`, all other events that a socket can emit to the server should be handled within the connecting listener where we have 'socket' defined.
 
-Submit your page when you think you've got it right. If you're running into errors, you can check out the project completed up to this point <a href='https://gist.github.com/camperbot/ab1007b76069884fb45b215d3c4496fa' target='_blank'>here</a>.
+Submit your page when you think you've got it right. If you're running into errors, you can check out the project completed up to this point [here](https://gist.github.com/camperbot/ab1007b76069884fb45b215d3c4496fa).
 
-</section>
+# --hints--
 
-## Instructions
+Server should handle the event disconnect from a socket.
 
-<section id='instructions'>
-
-</section>
-
-## Tests
-
-<section id='tests'>
-
-```yml
-tests:
-  - text: Server should handle the event disconnect from a socket.
-    testString: getUserInput => $.get(getUserInput('url')+ '/_api/server.js') .then(data => { assert.match(data, /socket.on.*('|")disconnect('|")/gi, ''); }, xhr => { throw new Error(xhr.statusText); })
-  - text: Your client should be listening for 'user count' event.
-    testString: getUserInput => $.get(getUserInput('url')+ '/public/client.js') .then(data => { assert.match(data, /socket.on.*('|")user count('|")/gi, 'Your client should be connection to server with the connection defined as socket'); }, xhr => { throw new Error(xhr.statusText); })
+```js
+(getUserInput) =>
+  $.get(getUserInput('url') + '/_api/server.js').then(
+    (data) => {
+      assert.match(data, /socket.on.*('|")disconnect('|")/gi, '');
+    },
+    (xhr) => {
+      throw new Error(xhr.statusText);
+    }
+  );
 ```
 
-</section>
+Your client should be listening for 'user count' event.
 
-## Challenge Seed
+```js
+(getUserInput) =>
+  $.get(getUserInput('url') + '/public/client.js').then(
+    (data) => {
+      assert.match(
+        data,
+        /socket.on.*('|")user count('|")/gi,
+        'Your client should be connection to server with the connection defined as socket'
+      );
+    },
+    (xhr) => {
+      throw new Error(xhr.statusText);
+    }
+  );
+```
 
-<section id='challengeSeed'>
+# --seed--
 
-</section>
-
-## Solution
-
-<section id='solution'>
+# --solutions--
 
 ```js
 /**
@@ -64,5 +68,3 @@ tests:
   Please check our contributing guidelines to learn more.
 */
 ```
-
-</section>