selinux: provide a "no sooner than" date for the checkreqprot removal

We marked /sys/fs/selinux/checkreqprot as deprecated in Linux v5.7,
but didn't provide any guidance as to the timeframe.  Considering
the state of checkreqprot, it seems like one year should be enough
time.
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Documentation/ABI/obsolete/sysfs-selinux-checkreqprot

@@ -15,7 +15,7 @@ Description:
 	actual protection), and Android and Linux distributions have been
 	explicitly writing a "0" to /sys/fs/selinux/checkreqprot during
 	initialization for some time.  Support for setting checkreqprot to 1
-	will be	removed in a future kernel release, at which point the kernel
+	will be	removed no sooner than June 2021, at which point the kernel
 	will always cease using checkreqprot internally and will always
 	check the actual protections being applied upon mmap/mprotect calls.
 	The checkreqprot selinuxfs node will remain for backward compatibility