Adds info about MONKEY pragma
Adds info about MONKEY pragma

Also deletes a section about "pragmas under discussion" that "will
probably never see the light". Closes #1707

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