Comments to help MAMP users on OSX

+1 on highlighting the `port`, but I agree with @josegonzalez on removing the line about MAMP. Perhaps replacing the comment with `CakePHP will use the default DB port based on the driver selected. If your database is using a non-standard port, uncomment the following line and set the port accordingly.` is a better option? Then highlight that "MAMP" uses port 8889 in the docs.