Fix footer and header to inherit from _layouts/default.html

Author: TimOsahenru

CONTRIBUTING.md

@@ -55,15 +55,17 @@ The diagram below explains how information is generated for the about page, show
 ```mermaid
     flowchart TD
     about.md --> _layouts/default.html
-    about.md --> _includes/header.html
-    about.md --> _includes/footer.html
     about.md --> _config.yml
+    _layouts/default.html --> _includes/header.html
+    _layouts/default.html --> _includes/footer.html
     _layouts/default.html --> about.html
     _config.yml --> about.html
     about.html --> assets/css/style.css
     about.html --> assets/js/script.js
 ```
 
+# How to Contribute
+
 ## Fork the repository
 
 - To fork the repository so you have a copy of the codebase, you will click on the **"Fork"** button from the repository main page