Address the python3 command issue on Windows

A lot of the support requests on pypa/packaging-problems are Windows users not being able to run the python3 command, since it is not shipped with the official CPython distribution. (recent example: pypa/packaging-problems#373)

Microsoft recently added a python3.exe stub that automatically opens the Windows Store page if you does not have the Store-provided Python installed. The problem is, the stub would silently do nothing if you pass any arguments to it, making users very confused.

I don’t have a perfect solution, unfortunately. The default python on macOS is still Python 2 (with a warning message), so that won’t work. py -3 is the recommended command for the official CPython distribution on Windows, but IIRC it is not shipped with the Windows Store distribution. The situation is quite bad, if I am being honest.

まず issue の本文とリンク先の例 pypa/packaging-problems#373 を確認し、ここで説明されている公式 CPython と Microsoft Store のコマンド動作を比較します。Windows ユーザー向けの具体的な推奨事項を定め、python3 引数の扱い方を文書化してください。未解決のコマンド選択に依存せず、報告された混乱に対処できるガイダンスになっていれば完了です。