add second PHP tutorial back

Author: KimberleyCook

index.html

@@ -94,6 +94,7 @@ <h3>PHP</h3>
 
         <ul>
           <li><a href="php/lesson1/tutorial.html">Lesson 1 - Introduction to PHP</a></li>
+          <li><a href="php/lesson2/tutorial.html">Lesson 2 - Values and Variables</a></li>
         </ul>
 
         <h2 class="language-heading">Apps</h2>