Help text and key for features-diff

I am constantly confusing myself with reading the output from features-diff. I got tired of using a post-it on my monitor to remember which is in code and which is in the database.

Here is a patch that outputs a short key when you run the features-diff command that tells you which is in code and which is in the database.

/**
 * Database. drush features-update if you want to keep
 * Code. drush features-revert if you want to keep
 **/

Hopefully others find this helpful as well.

I wasn't sure what the proper format should be for the output. I used drupal module header comment style but maybe there is something more appropriate for this situation.

Colin