Improve image alt text for accessibility

Updated the alt attribute of an image to provide a description.

Author: Zadri415

Wireframe/index.html

@@ -32,7 +32,7 @@ <h2>What is a Wireframe?</h2>
       </article>
 
       <article>
-        <img src="https://i0.wp.com/digitalvarys.com/wp-content/uploads/2019/06/image-6.png?fit=640%2C257&ssl=1" alt="" />
+        <img src="https://i0.wp.com/digitalvarys.com/wp-content/uploads/2019/06/image-6.png?fit=640%2C257&ssl=1" alt="Diagram showing Git branches diverging from the main branch" />
         <h2>What is a Branch in Git?</h2>
         <p>
           In Git, a branch is an independent line of development that allows you to work on new features or fixes without affecting the main codebase.