Update link to manning book (#14750)

* Fix link

* Handle site being blocked from azDO

docs/learning-powershell/README.md

@@ -115,7 +115,7 @@ Note that all bash commands should continue working on PowerShell session.
 [powershell-intro]: https://www.pluralsight.com/courses/powershell-intro
 [lynda-training]: https://www.lynda.com/PowerShell-training-tutorials/5779-0.html
 [learn-win-powershell]: https://www.amazon.com/Learn-Windows-PowerShell-Month-Lunches/dp/1617294160
-[learn-powershell]: https://www.manning.com/books/learn-powershell-in-a-month-of-lunches-linux-and-macos-edition
+[learn-powershell]: https://www.manning.com/books/learn-powershell-in-a-month-of-lunches
 
 [getstarted-with-powershell]: https://channel9.msdn.com/Series/GetStartedPowerShell3
 [why-learn-powershell]: https://blogs.technet.microsoft.com/heyscriptingguy/2014/10/18/weekend-scripter-why-learn-powershell/

test/common/markdown/markdown-link.tests.ps1

@@ -99,7 +99,8 @@ Describe "Verify Markdown Links" {
                         # check against the allowed failures
                         $allowedFailures = [System.Net.HttpStatusCode[]](
                             503, # Service Unavailable
-                            504  # Gateway Timeout
+                            504, # Gateway Timeout
+                            403  # Forbidden, some sites block with from AzDO with this code
                         )
 
                         $prefix = $url.Substring(0,7)