Merge pull request #1601 from coracle-social/nip29-join

Tweak group join requests to include user feedback

29.md

@@ -70,7 +70,7 @@ These are events that can be sent by users to manage their situation in a group,
 
 - *join request* (`kind:9021`)
 
-Any user can send one of these events to the relay in order to be automatically or manually added to the group. If the group is `open` the relay will automatically issue a `kind:9000` in response adding this user. Otherwise group admins may choose to query for these requests and act upon them.
+Any user can send a kind `9021` event to the relay in order to request admission to the group. Relays MUST reject the request if the user has not been added to the group. The accompanying error message SHOULD explain whether the rejection is final, if the request is pending review, or if some other special handling is relevant (e.g. if payment is required). If a user is already a member, the event MUST be rejected with `duplicate: ` as the error message prefix.
 
 ```json
 {