udpate deprecation banner

Author: FuhuXia

Gemfile.lock

@@ -246,4 +246,4 @@ DEPENDENCIES
   github-pages
 
 BUNDLED WITH
-   2.1.4
+   1.17.2

_includes/header.html

@@ -87,5 +87,11 @@
       practices, and schema standards to facilitate the adoption of open data
       practices across the Federal Government.
     </p>
+
+    <p>
+      Archived content of Project Open Data can be access at its <a href="https://github.com/project-open-data/project-open-data.github.io">Github repository</a>.
+      You can report missing content or provide any additional feedback via <a href="https://github.com/GSA/resources.data.gov/issues">Github</a>
+      or by emailing <a href="mailto:datagov@gsa.gov">datagov@gsa.gov</a>.
+    </p>
   </div>
 </div>