message: README: mention that you need to set PATH on windows.
diff: @@ -22,6 +22,8 @@ We currently support a variety of features.
  This extension requires an installation of [Lean](https://leanprover.github.io).
  +On windows, you may need to add `c:\msys64\mingw64\bin` (or wherever you installed msys2) to the system PATH environment variable.
  +
  ## Extension Settings
  This extension contributes the following settings:
  