Add -help to deploy_stack.ps1

Signed-off-by: John McCabe <john@johnmccabe.net>

deploy_stack.ps1

@@ -2,9 +2,19 @@
 
 param (
     [switch] $noAuth,
-    [switch] $n
+    [switch] $n,
+    [switch] $help,
+    [switch] $h
 )
 
+if ($help -Or $h) {
+    Write-Host "Usage: "
+    Write-Host " [default]`tdeploy the OpenFaaS core services"
+    Write-Host " -noAuth [-n]`tdisable basic authentication"
+    Write-Host " -help [-h]`tdisplays this screen"
+    Exit
+}
+
 if (Get-Command docker -errorAction SilentlyContinue)
 {
     docker node ls 2>&1 | out-null