refs #10283 - mark parameters advanced

Anything other than "Parameters" are not shown by default in Kafo help.
This makes the installer help shorter, and reduces the chance users will
change options that really shouldn't be changed unless you really really
really know what you're doing.

manifests/init.pp

@@ -4,7 +4,7 @@
 # aournd certificates generation and deployment. The per-subsystem configuratoin
 # of certificates should go into `subsystem_module/manifests/certs.pp`.
 #
-# === Parameters:
+# === Advanced parameters:
 #
 # $log_dir::              When the log files should go
 #