docs: cdrom-standard.tex: convert from LaTeX to ReST

This is the only LaTeX documentation file inside the documentation.

Instead of having a Latex document directly there, convert
it to ReST format, as this is the format we're using for docs.

For now, let's keep the extension as .txt in order to avoid
warnings when building the documentation with Sphinx.

The next patch patch will rename it to .rst and add it to the
building system.

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

drivers/cdrom/cdrom.c

@@ -7,7 +7,7 @@
    License.  See linux/COPYING for more information.
 
    Uniform CD-ROM driver for Linux.
-   See Documentation/cdrom/cdrom-standard.tex for usage information.
+   See Documentation/cdrom/cdrom-standard.txt for usage information.
 
    The routines in the file provide a uniform interface between the
    software that uses CD-ROMs and the various low-level drivers that