Add full-text search to Doxygen (#4994)

* Update hdf5doxy_layout.xml

Menu item for fulltext search.

* Update FTS.dox

Updated Google PSE ID.

Author: gheber

doxygen/dox/FTS.dox

@@ -1,8 +1,8 @@
 /** \page FTS Full-Text Search
 
 \htmlonly
-<script async src="https://cse.google.com/cse.js?cx=75c754173f9b90804"></script>
+<script async src="https://cse.google.com/cse.js?cx=f671574fa55cc44e6"></script>
 <div class="gcse-search"></div>
 \endhtmlonly
 
-*/
+*/

doxygen/hdf5doxy_layout.xml

@@ -14,6 +14,7 @@
     <tab type="user" url="@ref RFC" title="RFCs" />
     <tab type="user" url="@ref SPEC" title="Specifications" />
     <tab type="user" url="@ref GLS" title="Glossary" />
+    <tab type="user" url="@ref FTS" title="Full-Text Search" />
     <tab type="user" url="@ref About" title="About" />
   </navindex>