doc: document go1.2.2
doc: document go1.2.2

R=rsc, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/100110043

webfd/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,d0f/go-zh,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,webfd/go-zh,webfd/go-zh,bryanxu/go-zh,bryanxu/go-zh,bryanxu/go-zh,d0f/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,webfd/go-zh,bryanxu/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc