Document kernel taint flags properly

This fills in the documentation for all of the current kernel taint
flags, and fixes the number for TAINT_CRAP, which was incorrectly
described.

Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Documentation/sysctl/kernel.txt

@@ -369,5 +369,15 @@ can be ORed together:
    2 - A module was force loaded by insmod -f.
        Set by modutils >= 2.4.9 and module-init-tools.
    4 - Unsafe SMP processors: SMP with CPUs not designed for SMP.
- 64 - A module from drivers/staging was loaded.
+   8 - A module was forcibly unloaded from the system by rmmod -f.
+  16 - A hardware machine check error occurred on the system.
+  32 - A bad page was discovered on the system.
+  64 - The user has asked that the system be marked "tainted".  This
+       could be because they are running software that directly modifies
+       the hardware, or for other reasons.
+ 128 - The system has died.
+ 256 - The ACPI DSDT has been overridden with one supplied by the user
+        instead of using the one provided by the hardware.
+ 512 - A kernel warning has occurred.
+1024 - A module from drivers/staging was loaded.