Documentatio: HOWTO: remove regression postings info from translations

Obsolete info about regression postings were removed by commit
5645a717

 ("Documentation: HOWTO: remove
obsolete info about regression postings") but not applied to
translations.  This commit applies the change to translations.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>