Update index.html with author github profile.

Author: martinpulido

index.html

@@ -31,7 +31,7 @@ <h2 class="title-1 section-404-title">I have bad news for you</h2>
         </main>
 
         <footer class="footer">
-            <p><small>created by <a href="#" title="External link, open new tab to martinpulido profile" target="_blank">martinpulido</a> - devChallenges.io</small></p>
+            <p><small>created by <a href="https://github.com/martinpulido" title="External link, open new tab to martinpulido GitHub profile" target="_blank">martinpulido</a> - devChallenges.io</small></p>
         </footer>
 
     </div>