I've spent quite some time today trying to somehow override keybindings
for term-mode. While time was spent mostly due to some local mistakes,
one problem I also noticed is that term-mode has `term-mode-map` —
pretty much like any other major mode foo typically have `foo-mode-
map`. However, adding keybindings into it has no effect whatsoever.
Instead term-mode has an additional `term-raw-map`, which is the actual
location where one has to put custom bindings.

It is completely non-intuitive (and I also for some reason didn't get
the answer on emacs.stackexchange for the same problem when I was
trying to google it), so let's document that nuisance.