Fix embed link on homepage

Author: Ives van Hoorne

src/homepage/index.html

@@ -170,7 +170,7 @@ <h4>MobX-state-tree - TodoList by @mwestrate</h4>
 
     <div class="picked-project">
       <h4>Redux-First Router by @faceyspacey</h4>
-      <iframe src="https://codesandbox.io/s/github/faceyspacey/redux-first-router-codesandbox" style="width:100%; height:500px; border:0; border-radius: 4px; overflow:hidden;"
+      <iframe src="https://codesandbox.io/embed/github/faceyspacey/redux-first-router-codesandbox" style="width:100%; height:500px; border:0; border-radius: 4px; overflow:hidden;"
         sandbox="allow-modals allow-presentation allow-forms allow-popups allow-scripts allow-same-origin"></iframe>
     </div>
   </section>