Update documentation link on Update Center

On the Update Center, update the link to the documentation with a link to the Releases and Tags page and review the sentence.

"For production mode, it is recommended to install a <release of your project>. Available releases are listed below."

https://github.com/nuxeo/nuxeo/blob/master/nuxeo-features/nuxeo-platform-lang/src/main/resources/web/nuxeo.war/WEB-INF/classes/messages_en_US.properties