Documentation: fix formatting to make 's' happy

"That letter [the last s] is sad because all the others
have those things [=] below them and it does not."

This patch fixes the tragedy so all the letters can
be happy again.

Signed-off-by: Maisa Roponen <maisa.roponen@gmail.com>
[The author being 4 years old needed some assistance]
Signed-off-by: Tero Roponen <tero.roponen@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>