Update the note about the need for COMPAT_FREEBSD<n> kernel options.

Rather than mentioning the requirement for 4.x binaries but not
explaining why (it was assuming an upgrade from 4.x to 5.0-current),
explain when compat options are needed (for running existing host
binaries) in a more general way while using a more modern example
(COMPAT_FREEBSD11 for 11.x binaries).  While here, explicitly mention
that a GENERIC kernel should always work.

Reported by:	Robert Huff <roberthuff@rcn.com>
Reviewed by:	imp
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D18740

1 files changed, 7 insertions, 6 deletions

diff --git a/UPDATING b/UPDATING
index 836f94e93cf5..f720ed4e8ad2 100644
--- a/UPDATING
+++ b/UPDATING
@@ -1901,12 +1901,13 @@ COMMON ITEMS:
 	can be deleted by "make delete-old-libs", but you have to make
 	sure that no program is using those libraries anymore.
 
-	[8] In order to have a kernel that can run the 4.x binaries needed to
-	do an installworld, you must include the COMPAT_FREEBSD4 option in
-	your kernel.  Failure to do so may leave you with a system that is
-	hard to boot to recover. A similar kernel option COMPAT_FREEBSD5 is
-	required to run the 5.x binaries on more recent kernels.  And so on
-	for COMPAT_FREEBSD6 and COMPAT_FREEBSD7.
+	[8] The new kernel must be able to run existing binaries used by
+	an installworld.  When upgrading across major versions, the new
+	kernel's configuration must include the correct COMPAT_FREEBSD<n>
+	option for existing binaries (e.g. COMPAT_FREEBSD11 to run 11.x
+	binaries).  Failure to do so may leave you with a system that is
+	hard to boot to recover.  A GENERIC kernel will include suitable
+	compatibility options to run binaries from older branches.
 
 	Make sure that you merge any new devices from GENERIC since the
 	last time you updated your kernel config file.