Clarify Any.list
Clarify Any.list

Even though Any.list returns a List, clarify that subclasses can return
any Positional for this method.
stmuk/doc,dmaestro/doc,jonathanstowe/doc,MasterDuke17/doc,perl6/doc,perl6/doc,tbrowder/doc,tbrowder/doc,dmaestro/doc,MasterDuke17/doc,MasterDuke17/doc,dmaestro/doc,stmuk/doc,stmuk/doc,jonathanstowe/doc,stmuk/doc,perl6/doc,jonathanstowe/doc,jonathanstowe/doc,perl6/doc,perl6/doc,jonathanstowe/doc,tbrowder/doc,stmuk/doc,dmaestro/doc,MasterDuke17/doc,tbrowder/doc,dmaestro/doc