Update room-invitation.ts (#2104)
Update room-invitation.ts (#2104)

topic() returns a Promise<string> instead of Promise<Contact>. The document is incorrect.
mukaiu/wechaty,wechaty/wechaty,zixia/wechaty,zixia/wechaty,binsee/wechaty,mukaiu/wechaty,wechaty/wechaty,mukaiu/wechaty,wechaty/wechaty,binsee/wechaty,binsee/wechaty