add `nextdns-exporter` to list of exporters

[raylas]

Signed-off-by: Raymond Douglas [email protected]

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This is to add nextdns-exporter to the list of exporters.

NextDNS exporter scrapes the NextDNS API and surfaces DNS query data as Prometheus metrics.

Sample output

# HELP nextdns_allowed_queries_total Total number of allowed queries.
# TYPE nextdns_allowed_queries_total gauge
nextdns_allowed_queries_total{profile="7vsf3s"} 0
# HELP nextdns_blocked_queries Number of blocked queries per domain.
# TYPE nextdns_blocked_queries gauge
nextdns_blocked_queries{domain="app-measurement.com",profile="7vsf3s",root="",tracker=""} 2
nextdns_blocked_queries{domain="metrics.icloud.com",profile="7vsf3s",root="icloud.com",tracker=""} 5
# HELP nextdns_blocked_queries_total Total number of blocked queries.
# TYPE nextdns_blocked_queries_total gauge
nextdns_blocked_queries_total{profile="7vsf3s"} 7
# HELP nextdns_destination_queries Number of queries per geographic destination.
# TYPE nextdns_destination_queries gauge
nextdns_destination_queries{code="AU",name="Australia",profile="7vsf3s"} 1
nextdns_destination_queries{code="DE",name="Germany",profile="7vsf3s"} 6
nextdns_destination_queries{code="IE",name="Ireland",profile="7vsf3s"} 1
nextdns_destination_queries{code="US",name="United States of America",profile="7vsf3s"} 101
[...]