iterm: document how it all works
iterm: document how it all works

Because it is complicated enough that I can't remember what's going on
without looking at it all again to figure it out.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent