docs($location): hashPrefix, html5Mode are methods

Such getter-setter methods of $interpolateProvider are marked as methods, not properties.

Also, empty entries are generated for these members in the HTML output if they are marked as properties. See https://docs.angularjs.org/api/ng/provider/$locationProvider
![image](https://cloud.githubusercontent.com/assets/94334/3338436/d4112a20-f85b-11e3-982f-e0097fc53796.png)