Update Windows readme.txt to clarify Visual Studio required versions (pythonGH-99522)

This is just a minor update to add a clarification to the requirements in the Windows build readme.

Automerge-Triggered-By: GH:zooba

Author: BenJKuhn

PCbuild/readme.txt

@@ -1,7 +1,7 @@
 Quick Start Guide
 -----------------
 
-1.  Install Microsoft Visual Studio 2017 with Python workload and
+1.  Install Microsoft Visual Studio 2017 or later with Python workload and
     Python native development component.
 1a. Optionally install Python 3.6 or later.  If not installed,
     get_externals.bat (via build.bat) will download and use Python via