Restore filter on Windows and version reference for Windows facts.

system/setup.py

@@ -35,7 +35,7 @@ options:
         description:
             - path used for local ansible facts (*.fact) - files in this dir
               will be run (if executable) and their results be added to ansible_local facts
-              if a file is not executable it is read.
+              if a file is not executable it is read. Check notes for Windows options. (from 2.1 on)
               File/results format can be json or ini-format
         required: false
         default: '/etc/ansible/facts.d'
@@ -54,10 +54,13 @@ notes:
       install I(facter) and I(ohai) means you can avoid Ruby-dependencies on your
       remote systems. (See also M(facter) and M(ohai).)
     - The filter option filters only the first level subkey below ansible_facts.
+    - If the target host is Windows, you will not currently have the ability to use
+      C(filter) as this is provided by a simpler implementation of the module.
     - If the target host is Windows you can now use C(fact_path). Make sure that this path 
       exists on the target host. Files in this path MUST be PowerShell scripts (*.ps1) and 
       their output must be formattable in JSON (Ansible will take care of this). Test the 
       output of your scripts.
+      This option was added in Ansible 2.1.
 author:
     - "Ansible Core Team"
     - "Michael DeHaan"