Update content/client-server-api/_index.md

Signed-off-by: Johannes Marbach <n0-0ne+github@mailbox.org>

content/client-server-api/_index.md

@@ -2621,11 +2621,13 @@ An example of the capability API's response for this capability is:
 
 ### `m.forget_forced_upon_leave` capability
 
+{{% added-in v="1.18" %}}
+
 This capability has a single flag, `enabled`, which indicates whether or
 not the server automatically forgets rooms which the user has left.
 
 When `enabled` is `true` and the user leaves a room, the server will automatically
-forget the room – just as if the user had called [`/forget`](#post_matrixclientv3roomsroomidforget)
+forget the room — just as if the user had called [`/forget`](#post_matrixclientv3roomsroomidforget)
 themselves. This behavior applies irrespective of whether the user has left the
 room on their own (through [`/leave`](#post_matrixclientv3roomsroomidleave)) or
 has been kicked or banned from the room by another user.

data/api/client-server/capabilities.yaml

@@ -51,6 +51,7 @@ paths:
                         $ref: '#/components/schemas/booleanCapability'
                         description: Capability to indicate if the user can change their password.
                       m.forget_forced_upon_leave:
+                        x-addedInMatrixVersion: "1.18"
                         $ref: '#/components/schemas/booleanCapability'
                         description: |-
                           Capability to indicate if the server automatically forgets rooms once the user