Documentation: HOWTO: remove obsolete info about regression postings

corbet@lwn.net told me that these regression postings haven't happened for
several years. So i think we can remove it.
Signed-off-by: NPeter Loeffler <peter.loeffler@guruz.at>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/HOWTO

@@ -250,11 +250,6 @@ process is as follows:
     release a new -rc kernel every week.
   - Process continues until the kernel is considered "ready", the
     process should last around 6 weeks.
-  - Known regressions in each release are periodically posted to the 
-    linux-kernel mailing list.  The goal is to reduce the length of 
-    that list to zero before declaring the kernel to be "ready," but, in
-    the real world, a small number of regressions often remain at 
-    release time.
 
 It is worth mentioning what Andrew Morton wrote on the linux-kernel
 mailing list about kernel releases: