Fix relative URLs when serving the specification with a custom baseURL (#1984)

data/api/client-server/definitions/auth_data.yaml

@@ -21,7 +21,7 @@ properties:
       The authentication type that the client is attempting to complete.
       May be omitted if `session` is given, and the client is reissuing a
       request which it believes has been completed out-of-band (for example,
-      via the [fallback mechanism](#fallback)).
+      via the [fallback mechanism](/client-server-api/#fallback)).
     type: string
   session:
     description: The value of the session key given by the homeserver.

data/api/client-server/definitions/key_backup_session_data.yaml

@@ -28,7 +28,8 @@ properties:
     items:
       type: string
     description: |-
-      Chain of Curve25519 keys through which this session was forwarded, via [m.forwarded_room_key](#mforwarded_room_key) events.
+      Chain of Curve25519 keys through which this session was forwarded, via [m.forwarded_room_key](/client-server-api/#mforwarded_room_key)
+      events.
   sender_key:
     type: string
     description: |-

data/api/client-server/definitions/megolm_export_session_data.yaml

@@ -21,8 +21,8 @@ allOf:
       The format used to encode a Megolm session key for export.
 
       This is similar to the format before encryption used for the session keys
-      in [Server-side key backups](#server-side-key-backups) but adds the
-      `room_id` and `session_id` fields.
+      in [Server-side key backups](/client-server-api/#server-side-key-backups)
+      but adds the `room_id` and `session_id` fields.
     properties:
       room_id:
         type: string

data/api/client-server/definitions/timeline_batch.yaml

@@ -19,7 +19,7 @@ properties:
     type: boolean
   prev_batch:
     description: A token that can be supplied to the `from` parameter of the
-      [`/rooms/<room_id>/messages`](#get_matrixclientv3roomsroomidmessages)
+      [`/rooms/<room_id>/messages`](/client-server-api/#get_matrixclientv3roomsroomidmessages)
       endpoint in order to retrieve earlier events.
 
       If no earlier events are available, this property may be omitted from