Revised default notice for older versions. (#1528)

* Revised  default notice for older versions.

* Streamlined wording per review.

Author: debadair

lib/ES/Book.pm

@@ -15,8 +15,8 @@ use utf8;
 our %Page_Header = (
     en => {
         old => <<"HEADER",
-You are looking at documentation for an older release.
-Not what you want? See the
+<strong>IMPORTANT</strong>: No additional bug fixes or documentation updates 
+will be released for this version. For the latest information, see the 
 <a href="../current/index.html">current release documentation</a>.
 HEADER
         new => <<"HEADER"