Improve docs for infix:<∘>
Improve docs for infix:<∘>

- In math this is called function *composition*, so use more familiar terms
- Use `composed` as composed function name instead of `f-g`, which looks like a minus between two subs
- Fix the arity stuff: document that .count>1 routines get args slipped into them
- Include example for .count>1 version. Note that this version is NOT equivalent to 2.&g.&f
    as original example shows
perl6/doc,antquinonez/doc,gfldex/doc,MasterDuke17/doc,stmuk/doc,MasterDuke17/doc,jonathanstowe/doc,MasterDuke17/doc,dmaestro/doc,antquinonez/doc,perl6/doc,dmaestro/doc,dmaestro/doc,antquinonez/doc,gfldex/doc,gfldex/doc,stmuk/doc,antquinonez/doc,gfldex/doc,dmaestro/doc,jonathanstowe/doc,MasterDuke17/doc,gfldex/doc,perl6/doc,stmuk/doc,jonathanstowe/doc,stmuk/doc,perl6/doc,tbrowder/doc,jonathanstowe/doc,tbrowder/doc,tbrowder/doc,perl6/doc,dmaestro/doc,antquinonez/doc,stmuk/doc,tbrowder/doc,jonathanstowe/doc