document which field is which

util/src/entities/ReadState.ts

@@ -31,12 +31,15 @@ export class ReadState extends BaseClass {
 	})
 	user: User;
 
+	// fully read marker
 	@Column({ nullable: true })
-	last_message_id: string;
+	last_message_id: string; 
 	
+	// public read receipt
 	@Column({ nullable: true })
 	public_ack: string;
 
+	// notification cursor / private read receipt
 	@Column({ nullable: true })
 	notifications_cursor: string;