Embed Notice

@ProgGrrl @Beth @lakoja

- An instance can only show posts in the search that it knows of. (Exception: Using a Relay)
- Ways of knowing posts:
- - By users on that instance ("local posts")
- - By users followed by at least one user on that instance
- - Boosted by an user followed by at least one user on that instance
- - Searched for by URL by an user on that instance
- Instances remove remote posts after a certain time (Content cache retention period)
- All feeds are reverse chronological