Fix Push Gateway API example: Field renamed to event_id
I believe this was forgotten in:
@@ -57,7 +57,7 @@ paths:
type: object
example: {
"notification": {
- "id": "$3957tyerfgewrf384",
+ "event_id": "$3957tyerfgewrf384",
"room_id": "!slw48wfj34rtnrf:example.com",
"type": "m.room.message",
"sender": "@exampleuser:matrix.org",
