Added xmlns to the XML_PREAMBULA

The xmlns msh = 'http://msh' is required for xpath queries of provider
help to work. Added it to the XML_PREAMBULA

Author: adityapatwardhan

src/Markdown.MAML/Renderer/MamlRenderer.cs

@@ -18,7 +18,7 @@ public class MamlRenderer
         private Stack<string> _tagStack = new Stack<string>();
 
         public const string XML_PREAMBULA = @"<?xml version=""1.0"" encoding=""utf-8""?>
-<helpItems schema=""maml"">
+<helpItems xmlns=""http://msh"" schema=""maml"">
 ";
         public const string COMMAND_PREAMBULA = @"<command:command xmlns:maml=""http://schemas.microsoft.com/maml/2004/10"" xmlns:command=""http://schemas.microsoft.com/maml/dev/command/2004/10"" xmlns:dev=""http://schemas.microsoft.com/maml/dev/2004/10"" xmlns:MSHelp=""http://msdn.microsoft.com/mshelp"">";
 

test/Pester/PlatyPs.Tests.ps1

@@ -394,15 +394,18 @@ Describe 'New-ExternalHelp' {
         $Named
     }
 
-    It "generates right order for syntax" {
+    BeforeAll {
         $a = @{
             command = 'Test-OrderFunction'
             OutputFolder = 'TestDrive:\'
             Force = $true
         }
 
         $file = New-MarkdownHelp @a
-        $maml = $file | New-ExternalHelp -OutputPath "TestDrive:\" -Force
+        $maml = $file | New-ExternalHelp -OutputPath "TestDrive:\TestOrderFunction.xml" -Force
+    }
+
+    It "generates right order for syntax" {
         $help = Get-HelpPreview -Path $maml 
         ($help.Syntax.syntaxItem | measure).Count | Should Be 1
         $names = $help.Syntax.syntaxItem.parameter.Name
@@ -411,6 +414,11 @@ Describe 'New-ExternalHelp' {
         $names[1] | Should Be 'Third'
         $names[2] | Should Be 'Named'
     }
+
+    It "checks that xmlns 'http://msh' is present" {
+        $xml = [xml] (Get-Content (Join-Path $TestDrive 'TestOrderFunction.xml'))
+        $xml.helpItems.namespaceuri | Should Be 'http://msh'
+    }
 }
 
 #region PS Objects to MAML Model Tests