Document the notification API.

[endlisnis]

Is your feature request related to a problem? Please describe.

I'm an experienced software developer, with prior experience implementing and using REST APIs, but I found it challenging to understand how to request notifications because most of the calls and parameters are effectively undocumented.

For example, https://atproto.blue/en/latest/atproto/atproto_client.models.app.bsky.notification.list_notifications.html#atproto_client.models.app.bsky.notification.list_notifications.Params
The "priority" parameter is just documented with the word "Priority". That explanation gives me no idea what it does.
The "seen_at" parameter is just documented with the words "Seen at". Does that filter the returned notifications? Or does that mark them as seen? Some explanation would be nice.

Describe the solution you'd like
All parameters to all functions should have an explanation that describes what it does, not just repeating it's name.

Describe alternatives you've considered
I tried asking on Reddit about the meanings, and someone suggested that "priority" was just a shortcut for specifying a list of "reasons" as filters, but even they didn't know what "seen_at" meant.