Fix camelCased parameters (should use dash-case) in Usage section.

Fix camelCased parameters (should use dash-case) in Usage section.
Fix the link to angular/guide/ie that appears with "element" type directives.
Also added optional @prefix so if you like to have data- to pass html validators you can add @prefix data- to your doc blocks and all attributes will be prefixed with data- eg. data-attribute-name="value".