Update header.html

Add tools dropdown

Author: davidlange6

_includes/header.html

@@ -27,6 +27,15 @@
           <li class="dropdown-item"> <a class="nav-link" href="/tutorials">Tutorials</a></li>
         </ul>
       </li>
+
+      <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle" id="dropdown03" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Interactive Tools</a>
+        <ul class="dropdown-menu" aria-labelledby="dropdown03">         
+          <li class="dropdown-item"> <a class="nav-link" target="_blank" href="https://godbolt.org/z/3KWhY4j8M">Clad on Godbolt</a></li>
+          <li class="dropdown-item"> <a class="nav-link" target="_blank" href="https://compiler-research.org/xeus-cpp-wasm/lab/index.html">Xeus-CPP</a></li>
+        </ul>
+      </li>
+	    
       <li class="nav-item">
         <a class="nav-link" href="/team">Team</a>
       </li>