Doc patch, distinguish sections with an empty row in error code table

Hi,

This patch adds an empty row before each section header
in the error codes table in the docs.

I tried not putting an empty row before the first
section, but it looks better to always have
an empty row.  IMO.

File: errorcode_table.patch

Applies against head.

Regards,

Karl <kop@meme.com>
Free Software:  "You don't pay back, you pay forward."
                 -- Robert A. Heinlein