docs: Updating documentation for ndnSIM 2.5 release

Change-Id: Ia1dba06a9afd66a810171d4a512f35f6df6ba22a
diff --git a/docs/ns3_html_theme/ns3_doxy_header.html b/docs/ns3_html_theme/ns3_doxy_header.html
index 5f45f4f..2bb3c41 100644
--- a/docs/ns3_html_theme/ns3_doxy_header.html
+++ b/docs/ns3_html_theme/ns3_doxy_header.html
@@ -33,7 +33,7 @@
   </td>
   <td id="projecttext">
    <div id="projectbrief">NS-3 based Named Data Networking (NDN) simulator</div>
-   <span id="projectnumber">ndnSIM 2.3: NDN, CCN, CCNx, content centric networks</span>
+   <span id="projectnumber">ndnSIM 2.5: NDN, CCN, CCNx, content centric networks</span>
   </td>
   <!--BEGIN DISABLE_INDEX-->
    <!--BEGIN SEARCHENGINE-->