Rails and mysql adapter

[spk]

Following up on #195

For mysql/mariadb on RubyOnRails the adapter name is going to be mysql2 for most users, more info at https://guides.rubyonrails.org/configuring.html#configuring-a-mysql-or-mariadb-database

[akalipetis]

This will make sense in the context of a Rails stack. I've updated the labels so that we can keep this in mind when we start working on the Rails stack.