When reading the man page of e.g. 'mysql' on a system with MariaDB
installed one would actually see the man page of 'mariadb'. However the
man page had no indication of the page being for 'mariadb', which was
confusing for users.

Fix this by updating the man page title lines to use mariadb-* instead
of mysql* for MariaDB binaries that are drop-in replacements for MySQL
equivalents, indicating that the commands are actually of the MariaDB
version.

In long term, all the commands in man pages should be replaced by their
MariaDB counterparts. Update the title lines as a start, and only those
that exist as symlinks to their MariaDB counterparts.

Before:

    man mariadb-upgrade | head -n 1
    MYSQL_UPGRADE(1) ...

After:

    man mariadb-upgrade | head -n 1
    MARIADB-UPGRADE(1) ...

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.