[Maria-docs] tasks

I've tried to complete some simple tasks, but I know my edits need to be revised: https://kb.askmonty.org/en/create-event * Document ENABLE, DISABLE, and DISABLE ON SLAVE. * Document COMMENT. https://kb.askmonty.org/en/select * Document calling PROCUDURE in SELECT. I don't know if this is the best way to let you know... next time should I add a comment to the task page, instead? Federico