Add examples for how to use powershell common functions

lib/ansible/module_utils/powershell.ps1

@@ -29,6 +29,7 @@
 
 # Helper function to parse Ansible JSON arguments from a file passed as
 # the single argument to the module
+# Example: $params = Parse-Args $args
 Function Parse-Args($arguments)
 {
     $parameters = New-Object psobject;
@@ -42,6 +43,7 @@ Function Parse-Args($arguments)
 # Helper function to set an "attribute" on a psobject instance in powershell.
 # This is a convenience to make adding Members to the object easier and
 # slightly more pythonic
+# Example: Set-Attr $result "changed" $true
 Function Set-Attr($obj, $name, $value)
 {
     $obj | Add-Member -Force -MemberType NoteProperty -Name $name -Value $value
@@ -66,6 +68,7 @@ Function Get-Attr($obj, $name, $default = $null)
 
 # Helper function to convert a powershell object to JSON to echo it, exiting
 # the script
+# Example: Exit-Json $result
 Function Exit-Json($obj)
 {
     echo $obj | ConvertTo-Json
@@ -74,6 +77,7 @@ Function Exit-Json($obj)
 
 # Helper function to add the "msg" property and "failed" property, convert the
 # powershell object to JSON and echo it, exiting the script
+# Example: Fail-Json $result "This is the failure message"
 Function Fail-Json($obj, $message)
 {
     Set-Attr $obj "msg" $message
@@ -84,6 +88,7 @@ Function Fail-Json($obj, $message)
 
 # Helper filter/pipeline function to convert a value to boolean following current
 # Ansible practices
+# Example: $is_true = "true" | ConvertTo-Bool
 Function ConvertTo-Bool
 {
     param(