Sync eng/common directory with azure-sdk-tools for PR 2035 (Azure#20825)

* Add

* Add more description to docs of where the variable is consumed

Co-authored-by: Daniel Jurek <djurek@microsoft.com>

eng/common/scripts/Update-DocsMsPackages.ps1

@@ -18,10 +18,19 @@ packages which have not released to a central package manager.
 .PARAMETER DocRepoLocation
 Location of the docs.microsoft.com reference docs repo.
 
+.PARAMETER PackageSourceOverride
+Optional parameter to supply a different package source (useful for daily dev
+docs generation from pacakges which are not published to the default feed). This
+variable is meant to be used in the domain-specific business logic in
+&$UpdateDocsMsPackagesFn
+
 #>
 param (
   [Parameter(Mandatory = $true)]
-  $DocRepoLocation # the location of the cloned doc repo
+  [string] $DocRepoLocation, # the location of the cloned doc repo
+
+  [Parameter(Mandatory = $false)]
+  [string] $PackageSourceOverride
 )
 
 . (Join-Path $PSScriptRoot common.ps1)