MAINTAINERS: Hand over the release manager role to Oleksii Kurochko

I've finished the opportunity to do two releases (4.17 and 4.18)
and Oleksii Kurochko has volunteered to be the next release manager.
Hand over the role to him by changing the maintainership of the
CHANGELOG.md.

Signed-off-by: Henry Wang <Henry.Wang@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

MAINTAINERS

@@ -278,7 +278,7 @@ S:	Supported
 F:	xen/drivers/passthrough/arm/smmu-v3.c
 
 Change Log
-M:	Henry Wang <Henry.Wang@arm.com>
+M:	Oleksii Kurochko <oleksii.kurochko@gmail.com>
 R:	Community Manager <community.manager@xenproject.org>
 S:	Maintained
 F:	CHANGELOG.md