[io grant] Finish off IO::Handle.eof
[io grant] Finish off IO::Handle.eof

- Add `Defined as` bit
- IO::Handles can handle more than just files

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