Feat: add new Markdown parser (#39800)

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

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

@@ -1,15 +1,14 @@
 ---
-title: SEDOLs
 id: 59d9c6bc214c613ba73ff012
+title: SEDOLs
 challengeType: 5
 forumTopicId: 302305
 ---
 
-## Description
-<section id='description'>
+# --description--
+
+For each number list of 6-digit [SEDOL](https://en.wikipedia.org/wiki/SEDOL "wp: SEDOL")s, calculate and append the checksum digit. That is, given the input string on the left, your function should return the corresponding string on the right:
 
-For each number list of 6-digit <a href="https://en.wikipedia.org/wiki/SEDOL" title="wp: SEDOL" target="_blank">SEDOL</a>s, calculate and append the checksum digit.
-That is, given the input string on the left, your function should return the corresponding string on the right:
 <pre>
 710889 => 7108899
 B0YBKJ => B0YBKJ7
@@ -23,38 +22,44 @@ B0YBKR => B0YBKR5
 B0YBKT => B0YBKT7
 B00030 => B000300
 </pre>
-Check that each input is correctly formed, especially with respect to valid characters allowed in a SEDOL string. Your function should return <code>null</code> on an invalid input.
-</section>
 
-## Instructions
-<section id='instructions'>
+Check that each input is correctly formed, especially with respect to valid characters allowed in a SEDOL string. Your function should return `null` on an invalid input.
 
-</section>
+# --hints--
 
-## Tests
-<section id='tests'>
-
-```yml
-tests:
-  - text: <code>sedol</code> should be a function.
-    testString: assert(typeof sedol === 'function');
-  - text: <code>sedol('a')</code> should return null.
-    testString: assert(sedol('a') === null);
-  - text: <code>sedol('710889')</code> should return '7108899'.
-    testString: assert(sedol('710889') === '7108899');
-  - text: <code>sedol('BOATER')</code> should return null.
-    testString: assert(sedol('BOATER') === null);
-  - text: <code>sedol('228276')</code> should return '2282765'.
-    testString: assert(sedol('228276') === '2282765');
+`sedol` should be a function.
 
+```js
+assert(typeof sedol === 'function');
 ```
 
-</section>
+`sedol('a')` should return null.
 
-## Challenge Seed
-<section id='challengeSeed'>
+```js
+assert(sedol('a') === null);
+```
 
-<div id='js-seed'>
+`sedol('710889')` should return '7108899'.
+
+```js
+assert(sedol('710889') === '7108899');
+```
+
+`sedol('BOATER')` should return null.
+
+```js
+assert(sedol('BOATER') === null);
+```
+
+`sedol('228276')` should return '2282765'.
+
+```js
+assert(sedol('228276') === '2282765');
+```
+
+# --seed--
+
+## --seed-contents--
 
 ```js
 function sedol(input) {
@@ -63,15 +68,7 @@ function sedol(input) {
 }
 ```
 
-</div>
-
-
-
-</section>
-
-## Solution
-<section id='solution'>
-
+# --solutions--
 
 ```js
 function sedol(input) {
@@ -95,7 +92,4 @@ function sedolCheckDigit(char6) {
   const check = (10 - (sum % 10)) % 10;
   return check.toString();
 }
-
 ```
-
-</section>