MAINTAINERS: Update maintainers for new Documentaion/litmus-tests/

Also add me as Reviewer for LKMM. Previously a patch to do this was
Acked but somewhere along the line got lost. Add myself in this patch.

Acked-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index ebca5f6..0bebc63b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9711,6 +9711,7 @@
 M:	"Paul E. McKenney" <paulmck@kernel.org>
 R:	Akira Yokosawa <akiyks@gmail.com>
 R:	Daniel Lustig <dlustig@nvidia.com>
+R:	Joel Fernandes <joel@joelfernandes.org>
 L:	linux-kernel@vger.kernel.org
 L:	linux-arch@vger.kernel.org
 S:	Supported
@@ -9722,6 +9723,7 @@
 F:	Documentation/core-api/atomic_ops.rst
 F:	Documentation/core-api/refcount-vs-atomic.rst
 F:	Documentation/memory-barriers.txt
+F:	Documentation/litmus-tests/
 
 LIS3LV02D ACCELEROMETER DRIVER
 M:	Eric Piel <eric.piel@tremplin-utc.net>