misc/nacl: add debugging instructions
misc/nacl: add debugging instructions

LGTM=dave, minux
R=golang-codereviews, dave, minux
CC=golang-codereviews, rsc
https://codereview.appspot.com/122570043

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