[io grant] Finish off IO::Path.parts

- It now returns a Map, not a Hash
- :directory key is no longer there
- use Win32 path to showcase :volume
- Fix incorrect s/path/basename/ key name

Rakudo impl: rakudo/rakudo@9021a48665
             rakudo/rakudo@6ed14ef6fc
Tests: Raku/roast@fb61306aaa

Author: zoffixznet

doc/Type/IO/Path.pod6

@@ -281,13 +281,15 @@ the empty string.
 
 Defined as:
 
-    method parts(IO::Path:D: --> Hash)
+    method parts(IO::Path:D: --> Map:D)
 
-Returns a hash with the keys C<dirname>, C<path> and C<volume>, and as
-values the return values of the methods with the same names.
+Returns a L<Map> with the keys C<volume>, C<dirname>, C<basename> whose values
+are the same as available via methods L«C<.volume>|/routine/volume»,
+L«C<.dirname>|/routine/dirname», and L«C<.basename>|/routine/basename»
+respectively.
 
-    say IO::Path.new("/etc/passwd").parts.perl;
-    # OUTPUT: «{:basename("passwd"), :directory("/etc"), :dirname("/etc"), :volume("")}␤»
+    say IO::Path::Win32.new("C:/rakudo/perl6.bat").parts.perl;
+    # OUTPUT: «Map.new((:basename("perl6.bat"),:dirname("/rakudo"),:volume("C:")))␤»
 
 =head method gist