Fix dangling id to contribute button

Author: prertik

Diff for: index.html

@@ -99,7 +99,7 @@ <h3>Shell Integration</h3>
 			</div>
 		</div>
 	</section>
-	<section class="bg-light">
+	<section class="bg-light" id="contribute">
 		<div class="container">
 			<h2>Contribute</h2>
 			<p>As an open source project, Git for Windows benefits greatly from both the volunteer work of helpful
@@ -167,4 +167,4 @@ <h3><span class="gittext">Git for Windows SDK</span> : Contributing Code</h3>
 	</footer>
 </body>
 
-</html>
+</html>