Documentation/ABI: move sysfs-kernel-uids to removed directory

commit 7c941438 ("sched: Remove USER_SCHED") deleted the
USER_SCHED feature. so move the ABI doc to removed directory.
Signed-off-by: Wang Long <w@laoqinren.net>
Link: https://lore.kernel.org/r/1581082930-30441-1-git-send-email-w@laoqinren.netSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/ABI/testing/sysfs-kernel-uids → Documentation/ABI/removed/sysfs-kernel-uids

 What:		/sys/kernel/uids/<uid>/cpu_shares
-Date:		December 2007
+Date:		December 2007, finally removed in kernel v2.6.34-rc1
 Contact:	Dhaval Giani <dhaval@linux.vnet.ibm.com>
 		Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
 Description: