Document attribute aliases
Document attribute aliases

Part of the spec in Roast S12-class/attributes.t  
https://github.com/Raku/roast/blob/master/S12-class/attributes.t#L23-L33
MasterDuke17/doc,tbrowder/doc,tbrowder/doc,tbrowder/doc,MasterDuke17/doc,tbrowder/doc,MasterDuke17/doc,MasterDuke17/doc