Add PTR RFC4183 documentation link

diff --git a/src/ptr_equinix_dub_ipv4.js b/src/ptr_equinix_dub_ipv4.js
index 14be3f8f4f4183d5fb50cba1082c076e167257bd..ada63be280598aa358567b43c1cbf6fa3e720f64 100644 (file)
--- a/src/ptr_equinix_dub_ipv4.js
+++ b/src/ptr_equinix_dub_ipv4.js
@@ -1,3 +1,4 @@
+// http://www.he.net/adm/reverse.dns.html (RFC4183 notation)
 D(DOMAIN, REGISTRAR, DnsProvider(PROVIDER),
   PTR(SWITCH1DUB_IPV4.split(".").pop(), "switch1.dub.openstreetmap.org."),
   PTR(FAFNIR_IPV4.split(".").pop(), "fafnir.openstreetmap.org."),