fix(guide): restructure curriculum guide articles (#36501)

* fix: restructure certifications guide articles
* fix: added 3 dashes line before prob expl
* fix: added 3 dashes line before hints
* fix: added 3 dashes line before solutions

guide/english/certifications/coding-interview-prep/data-structures/create-a-set-class/index.md

@@ -1,32 +1,39 @@
 ---
 title: Create a Set Class
 ---
-## Create a Set Class
+# Create a Set Class
 
-### Method:
+---
+## Problem Explanation
 - A Set is an abstract data structure.
 - It can store unique value and the collection is unordered.
 - In this challenge, we have to implement `.add()` method. This method should only add unique values to `collection`.
   - The method should return `true`, if the value is sucessfully added to the collection, otherwise it should return `false`.
 
-### Solution:
+
+---
+## Solutions
+<details><summary>Solution 1 (Click to Show/Hide)</summary>
+
 ```js
 function Set() {
-    // the var collection will hold our set
-    var collection = [];
-    // this method will check for the presence of an element and return true or false
-    this.has = function(element) {
-        return (collection.indexOf(element) !== -1);
-    };
-    // this method will return all the values in the set
-    this.values = function() {
-        return collection;
-    };
-    this.add = function(el) {
-        return this.has(el) ? false : Boolean(collection.push(el));
-    }
+  // the var collection will hold our set
+  var collection = [];
+  // this method will check for the presence of an element and return true or false
+  this.has = function(element) {
+    return collection.indexOf(element) !== -1;
+  };
+  // this method will return all the values in the set
+  this.values = function() {
+    return collection;
+  };
+  this.add = function(el) {
+    return this.has(el) ? false : Boolean(collection.push(el));
+  };
 }
 ```
 
-### Resources:
+#### Relevant Links
 - [Wikipedia](https://en.wikipedia.org/wiki/Set_(abstract_data_type))
+
+</details>