Clarify the room-naming behaviour

Make behaviour on empty `m.room.name` and `m.room.canonical_alias` events
explicit.

event-schemas/schema/m.room.canonical_alias

@@ -1,7 +1,14 @@
 ---
 allOf:
   - $ref: core-event-schema/state_event.yaml
-description: This event is used to inform the room about which alias should be considered the canonical one. This could be for display purposes or as suggestion to users which alias to use to advertise the room.
+description: |-
+    This event is used to inform the room about which alias should be
+    considered the canonical one. This could be for display purposes or as
+    suggestion to users which alias to use to advertise the room.
+
+    A room with an ``m.room.canonical_alias`` event with an empty or absent
+    ``alias`` field should be treated the same as a room with no
+    ``m.room.canonical_alias`` event.
 properties:
   content:
     properties:
@@ -9,6 +16,8 @@ properties:
         description: The canonical alias.
         type: string
     type: object
+  required:
+    - alias
   state_key:
     description: A zero-length string.
     pattern: '^$'

event-schemas/schema/m.room.name

@@ -1,7 +1,17 @@
 ---
 allOf:
   - $ref: core-event-schema/state_event.yaml
-description: 'A room has an opaque room ID which is not human-friendly to read. A room alias is human-friendly, but not all rooms have room aliases. The room name 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. The room name can also be set when creating a room using ``/createRoom`` with the ``name`` key.'
+description: |-
+    A room has an opaque room ID which is not human-friendly to read. A room
+    alias is human-friendly, but not all rooms have room aliases. The room name
+    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 or empty ``name`` field
+    should be treated the same as a room with no ``m.room.name`` event.
+
+    An event of this type is automatically created when creating a room using
+    ``/createRoom`` with the ``name`` key.
 properties:
   content:
     properties: