Room list filtering

[KB1RD]

Currently, all rooms are displayed in the room list. This is a bad idea since the user can easily pick a room that has a long chat history and is not a document. There is talk of creating a room tag or similar for filtering by room type in the issue https://github.com/matrix-org/matrix-doc/issues/423.

[friedger]

Maybe include a special room event like for matrix-presents https://github.com/Half-Shot/matrix-presents/blob/master/docs/slide-theory.md

[KB1RD]

Added in v0.2.2. It is based on the typed rooms MSC (matrix-org/matrix-spec-proposals#1840).