capabilities.yaml: drop an extraneous title
AvailableRoomVersions sticks itself as a property type, preempting
the mention of RoomVersionStability in the generated text.
@@ -96,7 +96,6 @@ paths:
example: "1"
available:
type: object
- title: AvailableRoomVersions
description: |-
A detailed description of the room versions the server supports.
additionalProperties:
