Revises interpretation of win-verbatim-args #3561

Also refs #3495; not complete since `run` and `Proc.spawn` are still not processed.

doc/Type/Proc/Async.pod6

@@ -149,7 +149,8 @@ process arguments. See
 L<this blog|https://docs.microsoft.com/en-us/archive/blogs/twistylittlepassagesallalike/everyone-quotes-command-line-arguments-the-wrong-way>
 for more information on windows command quoting. The flag is ignored on all
 other platforms. The flag was introduced in Rakudo version 2020.06 and is not
-present in older releases.
+present in older releases. By default, it's set to C<False>, in which case
+arguments will be quoted according to Microsoft convention.
 
 =head2 method stdout