fix typo to use tsig in reflect demo server
fix typo to use tsig in reflect demo server

ezoic/dns,miekg/dns,tempbottle/dns,michaelharo/dns,asergeyev/dns,cloudflare/dns,curtiszimmerman/dns,jmhodges/dns,bragr/dns,tonnerre/golang-dns,skynet/dns,ym/go-dns,FiloSottile/dns,flebarbe/dns,Psiphon-Inc/dns,bboreham/dns,jdef/dns,josephyzhou/dns,janstk/dns,letsencrypt/dns,Git-Host/dns,AlexCheong/dns,skyportsystems/dns,benbearchen/dns,modulexcite/dns,hugozhu/dns,rolandshoemaker/dns,ErikDubbelboer/dns,tsenart/dns