fixed non-existing links

Author: blankRiot96

index.html

@@ -105,17 +105,17 @@ <h2>Learning Pygame</h2>
     </li>
 
     <li>
-      <a href="/guide/intro/setup">Chapter 10: The Pygame Input API</a>
+      <a href="/guide/intro/chapter-10/">Chapter 10: The Pygame Input API</a>
     </li>
 
     <li>
-      <a href="/guide/intro/setup">Chapter 11: Game States</a>
+      <a href="/guide/intro/chapter-11/">Chapter 11: Game States</a>
     </li>
     <li>
-      <a href="/guide/intro/setup">Chapter 12: Basic UI</a>
+      <a href="/guide/intro/chapter-12/">Chapter 12: Basic UI</a>
     </li>
     <li>
-      <a href="/guide/intro/setup">Chapter 13: Basic File Structure</a>
+      <a href="/guide/intro/chapter-13/">Chapter 13: Basic File Structure</a>
     </li>
   </ol>