Fix doc.perl6.org to docs.perl6.org.
Fix doc.perl6.org to docs.perl6.org.

While it should not be changed, being a statement, it is useful to
point to the right site.

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