Hi! I'm asking about a letter explaining kinship

I've arrived in Hangzhou 10 days ago with my husband he works here. we I'd the police check and they asked us to apply for my residence. among the papers needed "a letter explaining the kinship from the person being visited"
I don't know what to exactly write in this letter other than saying that that man is my husban. is there a template I can follow please? what should I include?