chore: add incomplete type for rich messages (#231)

Co-authored-by: Guilherme Gazzo <guilherme@gazzo.xyz>

Author: debdutdeb

packages/federation-sdk/src/index.ts

@@ -152,6 +152,17 @@ export type HomeserverEventSignatures = {
 							origin_server_ts: number;
 						};
 						is_falling_back?: boolean;
+				  }
+				| {
+						// SPEC: Though rich replies form a relationship to another event, they do not use rel_type to create this relationship.
+						// Instead, a subkey named m.in_reply_to is used to describe the reply’s relationship,
+
+						// rich {"body":"quote","m.mentions":{},"m.relates_to":{"is_falling_back":false,"m.in_reply_to":{"event_id":"$0vkvf2Ha_FdWe3zVaoDw3X15VCyZIZRYrHQXuoZDURQ"}},"msgtype":"m.text"}
+
+						'm.in_reply_to': {
+							event_id: EventID;
+						};
+						is_falling_back?: boolean;
 				  };
 			'm.new_content'?: {
 				body: string;