Clarify dispatch won't pick up native sizes
Clarify dispatch won't pick up native sizes

This and the already-existing prose around this section
close R#2316 https://github.com/rakudo/rakudo/issues/2316

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