MAINTAINERS: add nilfs2 git tree entry

NILFS2 filesystem section of the MAINTAINERS file lacks an entry of
scm tree.  This adds it.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

MAINTAINERS

@@ -4268,6 +4268,7 @@ NILFS2 FILESYSTEM
 M:	KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
 L:	linux-nilfs@vger.kernel.org
 W:	http://www.nilfs.org/en/
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2.git
 S:	Supported
 F:	Documentation/filesystems/nilfs2.txt
 F:	fs/nilfs2/