Fix for PDK validate, add parameter comments

It doesn't like having an optional parameter come before a non-optional
one. Since parameters are moving around a bit, add some comments to
clarify their intended usage.

Author: reidmv

manifests/setup/node_manager.pp

@@ -12,12 +12,21 @@
 #               }'
 #
 class peadm::setup::node_manager (
+  # Common
   String[1] $master_host,
-  String[1] $puppetdb_database_host = $master_host,
-
   String[1] $compiler_pool_address,
 
+  # High Availability
   Optional[String[1]] $master_replica_host            = undef,
+
+  # For the next two parameters, the default values are appropriate when
+  # deploying Standard or Large architectures. These values only need to be
+  # specified differently when deploying an Extra Large architecture.
+
+  # Specify when using Extra Large
+  String[1]           $puppetdb_database_host         = $master_host,
+
+  # Specify when using Extra Large AND High Availability
   Optional[String[1]] $puppetdb_database_replica_host = $master_replica_host,
 ) {