Remove additionalProperties: {} and note in description

changelogs/client_server/newsfragments/1910.clarification

@@ -1 +1 @@
-Update response schema of `GET /_matrix/client/v3/profile/{userId}` to clarify that properties other than `displayname` or `avatar_url` can be returned.
+Don't mention that `GET /_matrix/client/v3/profile/{userId}` can return additional properties because this is true for almost every endpoint.

data/api/client-server/profile.yaml

@@ -195,8 +195,7 @@ paths:
       description: |-
         Get the combined profile information for this user. This API may be used
         to fetch the user's own profile information or other users; either
-        locally or on remote homeservers. This API may return keys which are not
+        locally or on remote homeservers.
-        limited to `displayname` or `avatar_url`.
       operationId: getUserProfile
       parameters:
         - in: path
@@ -222,7 +221,6 @@ paths:
                     type: string
                     description: The user's display name if they have set one, otherwise not
                       present.
-                additionalProperties: {}
               examples:
                 response:
                   value: {