Corrected reference to RFC 1521, that was the wrong RFC to reference as it was obsoleted

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/codec/trunk@130132 13f79535-47bb-0310-9956-ffa450edef68

Author: Timothy O'Brien

xdocs/index.xml

@@ -42,7 +42,9 @@
       </td>
       <td>
        Provides Base64 content-transfer-encoding as defined in 
-       <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>
+       <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>. This
+       encoder can optionally create 76 character chunked output
+       for strict adherence to RFC 2045.
       </td>
       <td>
        Production