Windows/What's New: amend broken link in See Also

The first link under "See Also",
"What's New in Windows Server, version 1903" ,
is broken because it points to the wrong directory for the file
'whats-new-in-windows-server-1903' which resides in the new directory
/get-started-19/ instead of the old directory /get-started/.

This directory difference is only present in the docs.microsoft.com
pages, not on Github. The links are therefore pointing directly to the
docs.microsoft.com pages instead of being relative to the Github
directory structure.

Broken link:
https://docs.microsoft.com/windows-server/get-started/whats-new-in-windows-server-1903

Operative link:
https://docs.microsoft.com/windows-server/get-started-19/whats-new-in-windows-server-1903

Closes #4784

windows/whats-new/whats-new-windows-10-version-1903.md

@@ -144,7 +144,7 @@ Several new features are coming in the next version of Edge. See the [news from
 Several new features are coming in the next version of Edge. See the [news from Build 2019](https://blogs.windows.com/msedgedev/2019/05/06/edge-chromium-build-2019-pwa-ie-mode-devtools/#2QJF4u970WjQ2Sv7.97) for more information.
 
 ## See Also
-
+
 [What's New in Windows Server, version 1903](https://docs.microsoft.com/windows-server/get-started-19/whats-new-in-windows-server-1903): New and updated features in Windows Server.<br>
 [Windows 10 Features](https://www.microsoft.com/windows/features): Review general information about Windows 10 features.<br>
 [What's New in Windows 10](https://docs.microsoft.com/windows/whats-new/): See what’s new in other versions of Windows 10.<br>