docs: cdrom: convert docs to ReST and rename to *.rst

The stuff there is almost already at ReST format. A
conversion for them is trivial: just add a missing titles
and fix some scape codes for them to match ReST syntax.

While here, rename the cdrom-standard.txt, with was converted
from LaTeX to ReST on the previous patch, and add it to the
index file.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>