Refixing the syntax for @api-return to be more MSON-like.

[erunion]

This introduces a new, refined, syntax for @api-return annotations to make it more MSON-like and similar to other annotations within Mill.

Old

- @api-return:public {deleted}
- @api-return:public {notmodified} If no data has been changed.
- @api-return:public {collection} \Mill\Examples\Showtimes\Representations\Movie
- @api-return:public {collection} \Mill\Examples\Showtimes\Representations\Movie A collection of movies.

New

- @api-return:public deleted
- @api-return:public notmodified - If no data has been changed.
- @api-return:public collection (\Mill\Examples\Showtimes\Representations\Movie)
- @api-return:public collection (\Mill\Examples\Showtimes\Representations\Movie) - A collection of movies.