docs: sched-bwc.rst: fix a typo on a doc name

cgroupv2.rst -> cgroup-v2.rst
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/1dc0203bd7df375ef45832f0c88566e22c4138ff.1621413933.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/scheduler/sched-bwc.rst

@@ -29,7 +29,7 @@ Quota and period are managed within the cpu subsystem via cgroupfs.
 .. note::
    The cgroupfs files described in this section are only applicable
    to cgroup v1. For cgroup v2, see
-   :ref:`Documentation/admin-guide/cgroupv2.rst <cgroup-v2-cpu>`.
+   :ref:`Documentation/admin-guide/cgroup-v2.rst <cgroup-v2-cpu>`.
 
 - cpu.cfs_quota_us: the total available run-time within a period (in
   microseconds)