MAINTAINERS: Add Unicode tree

Unicode subsystem tree is missing from MAINTAINERS, add it.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>

Author: andrealmeid

MAINTAINERS

@@ -23443,6 +23443,7 @@ UNICODE SUBSYSTEM
 M:	Gabriel Krisman Bertazi <krisman@kernel.org>
 L:	linux-fsdevel@vger.kernel.org
 S:	Supported
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/krisman/unicode.git
 F:	fs/unicode/
 
 UNIFDEF