api comments for genres, studios, years, persons

MediaBrowser.Api/UserLibrary/GenresService.cs

@@ -13,6 +13,7 @@ namespace MediaBrowser.Api.UserLibrary
     /// </summary>
     [Route("/Users/{UserId}/Items/{Id}/Genres", "GET")]
     [Route("/Users/{UserId}/Items/Root/Genres", "GET")]
+    [ServiceStack.ServiceHost.Api(Description = "Gets all genres from a given item, folder, or the entire library")]
     public class GetGenres : GetItemsByName
     {
     }