mention arrays of arrays and slices of slices
mention arrays of arrays and slices of slices

Fixes issue 113.

R=gri, rsc
CC=golang-dev
http://codereview.appspot.com/159049

nightlyone/golang,dsriram/golang,gnanderson/go,bdwalton/debian-golang,bdwalton/debian-golang,apparentlymart/golang,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,ssrl/go,apparentlymart/golang,tv42/old-go,ssrl/go,bdwalton/debian-golang,dsriram/golang,apparentlymart/golang,h8liu/golang,tianon/debian-golang,dsriram/golang,gnanderson/go,ssrl/go,nightlyone/golang,tv42/old-go,pombredanne/go-deleteme,nightlyone/golang,nightlyone/golang,tianon/debian-golang,dsriram/golang,tianon/debian-golang,h8liu/golang,ssrl/go,gnanderson/go,bdwalton/debian-golang,tianon/debian-golang,tianon/debian-golang,pombredanne/go-deleteme,pombredanne/go-deleteme,h8liu/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,gnanderson/go,bdwalton/debian-golang,apparentlymart/golang,apparentlymart/golang,bdwalton/debian-golang,bdwalton/debian-golang,apparentlymart/golang,gnanderson/go,nightlyone/golang,h8liu/golang,gnanderson/go,nightlyone/golang,ssrl/go,dsriram/golang,tv42/old-go,tianon/debian-golang,pombredanne/go-deleteme,nightlyone/golang,h8liu/golang,tv42/old-go,bdwalton/debian-golang,tv42/old-go,dsriram/golang,h8liu/golang,ssrl/go,ssrl/go,tv42/old-go,tianon/debian-golang,tianon/debian-golang,dsriram/golang,gnanderson/go,h8liu/golang