reference Google Public DNS server

rule:
  meta:
    name: reference Google Public DNS server
    namespace: communication/dns
    authors:
      - william.ballenthin@mandiant.com
    scopes:
      static: function
      dynamic: thread
    references:
      - https://www.techradar.com/news/best-dns-server
      - https://developers.google.com/speed/public-dns/docs/using
  features:
    - or:
      - string: "8.8.8.8"
      - string: "8.8.4.4"
      - string: "2001:4860:4860::8888"
      - string: "2001:4860:4860::8844"