[io grant] Fix up IO::Path.basename
[io grant] Fix up IO::Path.basename

- it doesn't just return filename, since IO::Path can reference
    more than just files
- Point out semantics with Windows shares

MasterDuke17/doc,stmuk/doc,stmuk/doc,jonathanstowe/doc,antquinonez/doc,MasterDuke17/doc,dmaestro/doc,gfldex/doc,dmaestro/doc,MasterDuke17/doc,MasterDuke17/doc,dmaestro/doc,gfldex/doc,stmuk/doc,gfldex/doc,antquinonez/doc,tbrowder/doc,dmaestro/doc,perl6/doc,antquinonez/doc,jonathanstowe/doc,gfldex/doc,tbrowder/doc,jonathanstowe/doc,stmuk/doc,jonathanstowe/doc,perl6/doc,antquinonez/doc,dmaestro/doc,antquinonez/doc,perl6/doc,perl6/doc,perl6/doc,tbrowder/doc,tbrowder/doc,stmuk/doc,jonathanstowe/doc,gfldex/doc