Review and finish normalization subsection
Review and finish normalization subsection

It was pretty much completed by @samcv. I have added explicit
reference to graphemes and little more. Closes  #1517

Also deletes accidental markdown refs #2022.

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