solidify documentation of subscripts at /language/operators
solidify documentation of subscripts at /language/operators

The corresponding secions now provide a short overview / usage
demonstration, and link to /language/subscripts for further
details.
Also moved up the .[ ] section so that all subscript operator
sections are grouped together.

LLFourn/doc,MadcapJake/doc,jkeenan/doc,tbrowder/doc,perl6/doc,cygx/doc,muraiki/doc,muraiki/doc,gfldex/doc,MasterDuke17/doc,antquinonez/doc,dha/doc,antquinonez/doc,dnmfarrell/doc,MasterDuke17/doc,jonathanstowe/doc,stmuk/doc,gfldex/doc,dha/doc,LLFourn/doc,LLFourn/doc,dnmfarrell/doc,dnmfarrell/doc,dnmfarrell/doc,MasterDuke17/doc,antquinonez/doc,tbrowder/doc,jkeenan/doc,dnmfarrell/doc,dmaestro/doc,antquinonez/doc,stmuk/doc,perl6/doc,jonathanstowe/doc,muraiki/doc,perl6/doc,MadcapJake/doc,dha/doc,jkeenan/doc,cygx/doc,dha/doc,antquinonez/doc,jonathanstowe/doc,gfldex/doc,jkeenan/doc,cygx/doc,MadcapJake/doc,tbrowder/doc,perl6/doc,dmaestro/doc,MadcapJake/doc,stmuk/doc,jonathanstowe/doc,dha/doc,gfldex/doc,MadcapJake/doc,tbrowder/doc,dmaestro/doc,muraiki/doc,dmaestro/doc,stmuk/doc,cygx/doc,muraiki/doc,LLFourn/doc,jonathanstowe/doc,dmaestro/doc,cygx/doc,stmuk/doc,LLFourn/doc,MasterDuke17/doc,perl6/doc,jkeenan/doc,gfldex/doc