docs: fix API docs link at dyn.com

README.md

@@ -6,7 +6,7 @@ A small, lightweight and extensible DynDNS server written with Ruby and Rack.
 
 ## Description
 
-dyndnsd.rb aims to implement a small [DynDNS-compliant](http://dyn.com/support/developers/api/) server in Ruby supporting IPv4 and IPv6 addresses. It has an integrated user and hostname database in it's configuration file that is used for authentication and authorization. Besides talking the DynDNS protocol it is able to invoke an so-called *updater*, a small Ruby module that takes care of supplying the current host => ip mapping to a DNS server.
+dyndnsd.rb aims to implement a small [DynDNS-compliant](https://help.dyn.com/remote-access-api/) server in Ruby supporting IPv4 and IPv6 addresses. It has an integrated user and hostname database in it's configuration file that is used for authentication and authorization. Besides talking the DynDNS protocol it is able to invoke an so-called *updater*, a small Ruby module that takes care of supplying the current host => ip mapping to a DNS server.
 
 There is currently one updater shipped with dyndnsd.rb `command_with_bind_zone` that writes out a zone file in BIND syntax onto the current system and invokes a user-supplied command afterwards that is assumed to trigger the DNS server (not necessarily BIND since it's zone files are read by other DNS servers too) to reload it's zone configuration.