readme: remove too generic users (#1164)

These domain either nxdomain/404 or just generic sites selling some
service.

Remove them from the readme.

Signed-off-by: Miek Gieben <miek@miek.nl>

README.md

@@ -26,7 +26,6 @@ avoiding breaking changes wherever reasonable. We support the last two versions
 A not-so-up-to-date-list-that-may-be-actually-current:
 
 * https://github.com/coredns/coredns
-* https://cloudflare.com
 * https://github.com/abh/geodns
 * https://github.com/baidu/bfe
 * http://www.statdns.com/
@@ -42,11 +41,9 @@ A not-so-up-to-date-list-that-may-be-actually-current:
 * https://github.com/StalkR/dns-reverse-proxy
 * https://github.com/tianon/rawdns
 * https://mesosphere.github.io/mesos-dns/
-* https://pulse.turbobytes.com/
 * https://github.com/fcambus/statzone
 * https://github.com/benschw/dns-clb-go
 * https://github.com/corny/dnscheck for <http://public-dns.info/>
-* https://namesmith.io
 * https://github.com/miekg/unbound
 * https://github.com/miekg/exdns
 * https://dnslookup.org
@@ -55,19 +52,16 @@ A not-so-up-to-date-list-that-may-be-actually-current:
 * https://github.com/mehrdadrad/mylg
 * https://github.com/bamarni/dockness
 * https://github.com/fffaraz/microdns
-* http://kelda.io
 * https://github.com/ipdcode/hades <https://jd.com>
 * https://github.com/StackExchange/dnscontrol/
 * https://www.dnsperf.com/
 * https://dnssectest.net/
-* https://dns.apebits.com
 * https://github.com/oif/apex
 * https://github.com/jedisct1/dnscrypt-proxy
 * https://github.com/jedisct1/rpdns
 * https://github.com/xor-gate/sshfp
 * https://github.com/rs/dnstrace
 * https://blitiri.com.ar/p/dnss ([github mirror](https://github.com/albertito/dnss))
-* https://github.com/semihalev/sdns
 * https://render.com
 * https://github.com/peterzen/goresolver
 * https://github.com/folbricht/routedns