MAINTAINERS: add Roman as a memcg co-maintainer

Add myself as a memcg co-maintainer.  My primary focus over last few
years was the kernel memory accounting stack, but I do work on some
other parts of the memory controller as well.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

MAINTAINERS

@@ -4914,6 +4914,7 @@ CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)
 M:	Johannes Weiner <[email protected]>
 M:	Michal Hocko <[email protected]>
 M:	Vladimir Davydov <[email protected]>
+M:	Roman Gushchin <[email protected]>
 L:	[email protected]
 L:	[email protected]
 S:	Maintained