Mention to-device regression test

README.md

@@ -84,6 +84,7 @@ Network connectivity tests are extremely time sensitive as retries are often usi
 Regression tests:
  - [ ] Receive a to-device event with a room key, then fail requests to `/keys/query`. Ensure you can still see encrypted messages in that room. Regression test for https://github.com/vector-im/element-web/issues/24682
  - [ ] Receive many to-device events followed by a room key, then quickly restart the client. Ensure you can still see encrypted messages in that room. Tests that to-device events are persisted locally or the since token is not advanced before processing to avoid dropped to-device events. Regression test for https://github.com/vector-im/element-web/issues/23113
+ - [ ] If you make a new room key, you need to send it to all devices in the room. If you restart the client mid-way through sending, ensure the rest get sent upon restart.
  - [ ] Tests for [MSC3061](https://github.com/matrix-org/matrix-spec-proposals/pull/3061): Sharing room keys for past messages. Rust SDK: https://github.com/matrix-org/matrix-rust-sdk/issues/580
 
  These tests may require reverse proxy interception to let some requests pass through but not others.