[gjs/update-msvc-build-docs] README.MSVC.md: Mention about introspection workarounds

[Chun-wei Fan <fanchunwei src gnome org>]

commit 48996e4642bcee541dfe858dbffc933fbe7e97d1
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Thu Aug 11 17:44:41 2022 +0800

    README.MSVC.md: Mention about introspection workarounds
    
    The distutils that is provided with setuptools can have problems coping with
    running the introspection builds for GJS, so mention a workaround while a
    fix is being investigated.

 README.MSVC.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/README.MSVC.md b/README.MSVC.md
index ffb356d49..68b5e1602 100644
--- a/README.MSVC.md
+++ b/README.MSVC.md
@@ -170,7 +170,9 @@ meson <path_to_gjs_sources> --buildtype=... --prefix=<some_prefix> -Dskip_dbus_t
 see the Meson documentation for the values accepted by buildtype)
 
 You may want to view the build options after the configuration succeeds
-by using 'meson configure'
+by using 'meson configure'.  You may need to set the envvar:
+`SETUPTOOLS_USE_DISTUTILS=stdlib` for the introspection step to proceed
+successfully.  A fix for this is being investigated.
 
 When the configuration succeeds, run:
 ninja