Add note about using hostnames on IPv6 systems

config/code_ocean.yml.example

@@ -41,6 +41,8 @@ default: &default
     # The strategy to use. Possible values are: poseidon, docker_container_pool
     strategy: poseidon
     # The root URL of the runner management to use
+    # If a hostname is specified and the target host is reachable via IPv6, the WebSocket
+    # connection might not use the IPv6-to-IPv4 fallback but rather fail unexpectedly.
     url: https://runners.example.org
     # The root certificate authority to trust for TLS connections to the runner management (Poseidon only)
     ca_file: /example/certificates/ca.crt