Set correct api group description

[RoMiRoSSaN]

See #2173

Hi. Schema build generate not correct description on api group. For example if use this code

@Description("Group description")
@Name("Group")
@GraphQLApi
public class Api {
    @Query
    @Description("Method description")
    public String method() {
        return "method";
    }
}

wiil be generated next part of schema, which contains first available description (it takes description from method, becouse in annotation instances it is first element)

"Method description"
type GroupQuery {
  "Method description"
  method: String
}
///

Need check that annotation instance target equals api class