Update stable tree documentation

Update the documentation for the stable tree rules to reflect
that device IDs and quirks are also suitable for -stable
kernels.
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Documentation/stable_kernel_rules.txt

@@ -12,6 +12,7 @@ Rules on what kind of patches are accepted, and which ones are not, into the
    marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
    security issue, or some "oh, that's not good" issue.  In short, something
    critical.
+ - New device IDs and quirks are also accepted.
  - No "theoretical race condition" issues, unless an explanation of how the
    race can be exploited is also provided.
  - It cannot contain any "trivial" fixes in it (spelling changes,