Documentation/SubmitChecklist: convert it to ReST markup

- use ``foo`` to markup inline literal stuff, effectively making it
  to be presented as a monospaced font when parsed by Sphinx;

- the markup below the title should have the same length as the
  title;

- Fix the list markups, from "1:" to "1)";

- Split item 2 into a separate list for the build options, in order
  to be presented as a list on Sphinx;

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