add PSE box to sidebar

Author: loricooperhdf

_layouts/default.html

@@ -52,6 +52,12 @@
         </ul>
         {% endif %}
         -->
+
+        <h3>Search</h3>
+
+        <script async src="https://cse.google.com/cse.js?cx=f671574fa55cc44e6">
+        </script>
+        <div class="gcse-search"></div>
 
         <h3>Got HDF5?</h3>
         <a href="https://myhdf5.hdfgroup.org/"><img src="/assets/img/view-HDF5-file-in-browser.png" alt="Visualization of an HDF5 file"></a>