Document custom rke config in settings.yml.example

ansible/group_vars/all/settings.yml.example

@@ -19,3 +19,12 @@ helmfiles:
   - 10-nginx
   - 15-monitoring
   - 20-nextcloud
+# Optional, custom rke config. I.e., allow disabling ipv6 in pods by
+# passing adding an additional argument to the kubelet:
+# `--allowed-unsafe-sysctls net.ipv6.conf.all.disable_ipv6`
+#
+# rke_custom_config:
+#   services:
+#     kubelet:
+#       extra_args:
+#         allowed-unsafe-sysctls: 'net.ipv6.conf.all.disable_ipv6'