* Add rough documentation for `/api/v2_alpha/notifications`
* Update notifications_alpha.md
* Add very rough documentation about notification groups entities
* Add documentation for `NotificationGroup` entity
* Document pagination-only `NotificationGroup` attributes
* Fix documentation issue with `/api/v2_alpha/notifications/:group_key` and add example output
* Add blurb about the goal of grouped notifications
* Update notifications_alpha.md
* Specify that the 80 limit is for notification groups, not notifications
* Add documentation for `group_key` to `Notification` entity
* Make `max_id`, `since_id` and `min_id` more explicit