go.text/collate/colltab: doc update.
go.text/collate/colltab: doc update.

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/89420043

bryanxu/go-zh.text,d0f/go-zh.text,ssor/normGo,scalingdata/go.text,webfd/go-zh.text