Improve CUR::FileSystem example
Improve CUR::FileSystem example

Fixes #2766

perl6/doc,perl6/doc,MasterDuke17/doc,perl6/doc,perl6/doc,tbrowder/doc,tbrowder/doc,tbrowder/doc,MasterDuke17/doc,tbrowder/doc,MasterDuke17/doc,MasterDuke17/doc,perl6/doc