Documentation/SubmittingPatches: enrich the Sphinx output

Do a few changes to make the output look better:

- use bullets on trivial patches list;
- use monotonic font for tools name;
- use :manpage:`foo` for man pages;
- don't put all references to maintainer*html at the same line.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>