Comments to help MAMP users on OSX

The original goal of this change was to 1) Highlight the optional 'port' => 'xxxx' setting since it's not in there by default
and 2) make it easier for people to get started with CakePHP, with the thought that quite a few people on OSX use MAMP and could use a little help in the configuration part.

What's the best way to go about that?