BACKPORT: tee.txt: standardize document format

BACKPORT: tee.txt: standardize document format

Each text file under Documentation follows a different format. Some
doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- adjust identation of titles;
- mark ascii artwork as a literal block;
- adjust references.

Change-Id: I5d410e1fae61bbc240de47f6837730100519fda8
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
(cherry picked from commit 4297739f2b5d4693d9b9f9e3dffeecf2ae9f8081)
Signed-off-by: Victor Chong <victor.chong@linaro.org>