add wireframe alt text

Author: edinakurdi

Wireframe/index.html

@@ -26,7 +26,7 @@ <h2>What is a README file?</h2>
     </article>
 
     <article>
-      <img src="https://live.staticflickr.com/2154/5734993652_d4a2ee8778_b.jpg" alt="" />
+      <img src="https://live.staticflickr.com/2154/5734993652_d4a2ee8778_b.jpg" alt="wireframe sketch of website layout" />
       <h2>What is the purpose of a wireframe?</h2>
       <p>
         A wireframe for a website is like a blueprint for a house. It is a visual representation of the layout of the website. It is useful for planning purposes and can save time before building, by helping us spot potential issues early.