doc: document support building with Python 3.10 on Windows

PR-URL: #41098
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Derek Lewis <DerekNonGeneric@inf.is>

BUILDING.md

@@ -570,7 +570,7 @@ to run it again before invoking `make -j4`.
 
 ##### Option 1: Manual install
 
-* [Python 3.9](https://www.microsoft.com/en-us/p/python-39/9p7qfqmjrfp7)
+* [Python 3.10](https://www.microsoft.com/en-us/p/python-310/9pjpw5ldxlz5)
 * The "Desktop development with C++" workload from
   [Visual Studio 2019](https://visualstudio.microsoft.com/downloads/) or
   the "C++ build tools" workload from the