docs: add new LeetCode problem documentation and cleanup formatting

docs/reference/01-reverse-string.mdx

@@ -31,7 +31,6 @@ You must do this by modifying the input array in-place with O(1) extra memory.
  * @param {character[]} s
  * @return {void} Do not return anything, modify s in-place instead.
  */
-
 var reverseString = function(s) {
     let i = 0;
     let j = s.length - 1;