docs: New matrix invite procedure (#1554)

Author: Nannk

matrix.md

@@ -1,7 +1,10 @@
-To get invited to ani-cli matrix space send an email to `8klv0leh7 at mozmail.com` with the following contents:
-```
-Subject: ani-cli matrix space invite
-Body: @yourusername:matrixserver
-```
+To get invited to ani-cli matrix space please knock into the `#ani-cli-queue:matrix.org` room.
+
+In the reason field, please mention that you want to be invited to ani-cli.
+If your main client does not support spaces, please add that to the reason.
+
+Knocking is not supported by every client yet. You can use nheko.
+In nheko, click on a `plus icon` in the down left corner, `join room`, input `#ani-cli-queue:matrix.org` into the "Room ID or alias" input box.
+It will say that you are not allowed to join and ask if you want to knock.
 
 It might take some time before you get invited.