(GH-116) Clarify New-ExternalHelpCab is Windows-only (#117)

Prior to this change, the documentation didn't state that the PlatyPS
cmdlet `New-ExternalHelpCab` only works on Windows, despite requiring
the `MakeCab.exe` native command, which is only available on Windows.

This change adds a notice to the cmdlet documentation to clarify this
limitation.

- Resolves #116
- Fixes AB#41454

reference/ps-modules/PlatyPS/New-ExternalHelpCab.md

@@ -9,40 +9,50 @@ schema: 2.0.0
 # New-ExternalHelpCab
 
 ## SYNOPSIS
-Generates a .cab file.
+Generates a `.cab` file.
 
 ## SYNTAX
 
 ```
-New-ExternalHelpCab -CabFilesFolder <String> -LandingPagePath <String> -OutputFolder <String>
+New-ExternalHelpCab -CabFilesFolder <String> -LandingPagePath <String>
+ -OutputFolder <String>
  [-IncrementHelpVersion] [<CommonParameters>]
 ```
 
 ## DESCRIPTION
 
-The `New-ExternalHelpCab` cmdlet generates a .cab file that contains all the non-recursive content
+The `New-ExternalHelpCab` cmdlet generates a `.cab` file that contains all the non-recursive content
 in a folder. This cmdlet compresses the provided files.
 
+> [!NOTE]
+> This cmdlet depends on the `MakeCab.exe` native command, which is only available on Windows. This
+> cmdlet raises an error if used on non-Windows machines.
+
 We recommend that you provide as content only about_ topics and the output from the
 [New-ExternalHelp](New-ExternalHelp.md) cmdlet to this cmdlet.
 
-This cmdlet uses metadata stored in the module markdown file to name your .cab file. This naming
-matches the pattern that the Windows PowerShell help system requires for use as updatable help. This
+This cmdlet uses metadata stored in the module markdown file to name your `.cab` file. This naming
+matches the pattern that the PowerShell help system requires for use as updatable help. This
 metadata is part of the module file created using the [New-MarkdownHelp](New-MarkdownHelp.md)
 cmdlet with the **WithModulePage** parameter.
 
 This cmdlet also generates or updates an existing `helpinfo.xml` file. That file provides versioning
-and locale details to the Windows PowerShell help system.
+and locale details to the PowerShell help system.
 
 ## EXAMPLES
 
 ### Example 1: Create a CAB file
 
 ```powershell
-New-ExternalHelpCab -CabFilesFolder 'C:\Module\ExternalHelpContent' -LandingPagePath 'C:\Module\ModuleName.md' -OutputPath 'C:\Module\Cab\'
+$params = @{
+    CabFilesFolder  = 'C:\Module\ExternalHelpContent'
+    LandingPagePath = 'C:\Module\ModuleName.md'
+    OutputPath      = 'C:\Module\Cab\'
+}
+New-ExternalHelpCab @params
 ```
 
-This commmand creates a `.cab` file that contains the content folder files. The `.cab` file is named
+The cmdlet creates a `.cab` file that contains the content folder files. The `.cab` file is named
 for updatable help based on metadata. The command places the `.cab` file in the output folder.
 
 ## PARAMETERS
@@ -65,8 +75,8 @@ Accept wildcard characters: False
 
 ### -LandingPagePath
 
-Specifies the full path of the Module Markdown file that contains all the metadata required to name
-the .cab file. For the required metadata, run `New-MarkdownHelp` with the **WithLandingPage**
+Specifies the full path of the module Markdown file that contains all the metadata required to name
+the `.cab` file. For the required metadata, run `New-MarkdownHelp` with the **WithLandingPage**
 parameter.
 
 ```yaml
@@ -99,7 +109,7 @@ Accept wildcard characters: False
 
 ### -IncrementHelpVersion
 
-Automatically increment the help version in the module markdown file.
+Automatically increment the help version in the module Markdown file.
 
 ```yaml
 Type: SwitchParameter