diff --git a/doc/main.conf b/doc/main.conf
index e85aab10..793c45ac 100644
--- a/doc/main.conf
+++ b/doc/main.conf
@@ -31,6 +31,7 @@
 # the system resolving service.  The currently supported services are:
 # - systemd-resolved ["systemd"]
 # - openresolv / resolvconf ["resolvconf"]
+# - none
 #
 # If not set, the value "systemd" is used by default.  Uncomment the value
 # below if you are using openresolv: