Change 6.d FAQ
Change 6.d FAQ

- Clarify the expectations for new features
- Remove 6.d-prep repo; it's not for users
- Be less vague about release date
MasterDuke17/doc,jonathanstowe/doc,dmaestro/doc,jonathanstowe/doc,perl6/doc,jonathanstowe/doc,MasterDuke17/doc,dmaestro/doc,dmaestro/doc,tbrowder/doc,dmaestro/doc,jonathanstowe/doc,stmuk/doc,stmuk/doc,perl6/doc,dmaestro/doc,stmuk/doc,MasterDuke17/doc,perl6/doc,tbrowder/doc,perl6/doc,stmuk/doc,tbrowder/doc,perl6/doc,stmuk/doc,jonathanstowe/doc,MasterDuke17/doc,tbrowder/doc