Javascript: Added hint to Check for All or None (#19255)

Added hint to Check for All or None (https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/regular-expressions/check-for-all-or-none and https://guide.freecodecamp.org/certifications/javascript-algorithms-and-data-structures/regular-expressions/check-for-all-or-none/)

client/src/guide/english/certifications/javascript-algorithms-and-data-structures/regular-expressions/check-for-all-or-none/index.md

@@ -1,10 +1,20 @@
----
-title: Check for All or None
----
+
 ## Check for All or None
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/javascript-algorithms-and-data-structures/regular-expressions/check-for-all-or-none/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
-
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
-
 <!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->
+
+## The Problem:
+
+We need to change the regex ```favRegex``` to match both the American English (favorite) and the British English (favourite) version of the word.
+
+  ## Solution:
+ 
+ ```js
+let favWord = "favorite";
+let favRegex = /favou?rite/; // Change this line
+let result = favRegex.test(favWord);
+```
+
+  ## Explanation:
+ 
+In this regex (```/favou?rite/```), we specify the possible existence of an element (```u```) with a question mark, ```?```.