Clarify that an `m.room.name` event with an absent `name` field is not expected behavior (#1639)

Fixes #1632

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

changelogs/client_server/newsfragments/1639.clarification

@@ -0,0 +1 @@
+Clarify that an `m.room.name` event with an absent `name` field is not expected behavior.

data/event-schemas/schema/m.room.name.yaml

@@ -7,9 +7,8 @@ description: |-
     is a human-friendly string designed to be displayed to the end-user. The
     room name is not unique, as multiple rooms can have the same room name set.
 
-    A room with an `m.room.name` event with an absent, null, or empty
+    If a room has an `m.room.name` event with an absent, null, or empty `name`
-    `name` field should be treated the same as a room with no `m.room.name`
+    field, it should be treated the same as a room with no `m.room.name` event.
-    event.
 
     An event of this type is automatically created when creating a room using
     `/createRoom` with the `name` key.