add zdns as a user of miekg/dns (#1608)

Author: phillip-stephens

README.md

@@ -85,6 +85,7 @@ A not-so-up-to-date-list-that-may-be-actually-current:
 * https://github.com/wintbiit/NineDNS
 * https://linuxcontainers.org/incus/
 * https://ifconfig.es
+* https://github.com/zmap/zdns
 
 
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