Feat: add new Markdown parser (#39800)

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

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/ackermann-function.md

@@ -1,47 +1,59 @@
 ---
-title: Ackermann function
 id: 594810f028c0303b75339acf
+title: Ackermann function
 challengeType: 5
 forumTopicId: 302223
 ---
 
-## Description
-<section id='description'>
+# --description--
+
 The Ackermann function is a classic example of a recursive function, notable especially because it is not a primitive recursive function. It grows very quickly in value, as does the size of its call tree.
+
 The Ackermann function is usually defined as follows:
-$A(m, n) = \begin{cases} n+1 & \mbox{if } m = 0 \\ A(m-1, 1) & \mbox{if } m > 0 \mbox{ and } n = 0 \\ A(m-1, A(m, n-1)) & \mbox{if } m > 0 \mbox{ and } n > 0. \end{cases}$
+
+$A(m, n) = \\begin{cases} n+1 & \\mbox{if } m = 0 \\\\ A(m-1, 1) & \\mbox{if } m > 0 \\mbox{ and } n = 0 \\\\ A(m-1, A(m, n-1)) & \\mbox{if } m > 0 \\mbox{ and } n > 0. \\end{cases}$
+
 Its arguments are never negative and it always terminates.
-</section>
 
-## Instructions
-<section id='instructions'>
+# --instructions--
+
 Write a function which returns the value of $A(m, n)$. Arbitrary precision is preferred (since the function grows so quickly), but not required.
-</section>
 
-## Tests
-<section id='tests'>
+# --hints--
 
-```yml
-tests:
-  - text: <code>ack</code> should be a function.
-    testString: assert(typeof ack === 'function');
-  - text: <code>ack(0, 0)</code> should return 1.
-    testString: assert(ack(0, 0) === 1);
-  - text: <code>ack(1, 1)</code> should return 3.
-    testString: assert(ack(1, 1) === 3);
-  - text: <code>ack(2, 5)</code> should return 13.
-    testString: assert(ack(2, 5) === 13);
-  - text: <code>ack(3, 3)</code> should return 61.
-    testString: assert(ack(3, 3) === 61);
+`ack` should be a function.
 
+```js
+assert(typeof ack === 'function');
 ```
 
-</section>
+`ack(0, 0)` should return 1.
 
-## Challenge Seed
-<section id='challengeSeed'>
+```js
+assert(ack(0, 0) === 1);
+```
 
-<div id='js-seed'>
+`ack(1, 1)` should return 3.
+
+```js
+assert(ack(1, 1) === 3);
+```
+
+`ack(2, 5)` should return 13.
+
+```js
+assert(ack(2, 5) === 13);
+```
+
+`ack(3, 3)` should return 61.
+
+```js
+assert(ack(3, 3) === 61);
+```
+
+# --seed--
+
+## --seed-contents--
 
 ```js
 function ack(m, n) {
@@ -49,21 +61,10 @@ function ack(m, n) {
 }
 ```
 
-</div>
-
-
-
-</section>
-
-## Solution
-<section id='solution'>
-
+# --solutions--
 
 ```js
 function ack(m, n) {
   return m === 0 ? n + 1 : ack(m - 1, n === 0 ? 1 : ack(m, n - 1));
 }
-
 ```
-
-</section>