www/onlyoffice-documentserver: Improve port.
- Option'ify the database backend and add MySQL
- Add a newsyslog sample file (pr 261514, submitted by Martin Waschbüsch)
- Add a missing nginx sample file (ds-ssl.conf)
- Fix an hardcoded /usr/local in files/patch-document-server-package_Makefile
- Improve pkg-message:
- Add an 'upgrade' note (suggested by bapt@)
- Add instructions to use MySQL as a database server
- Pass the erlang-cookie option when invoking rabbitmqctl
PR: 261514