MAINTAINERS: update overlayfs git tree

Overlayfs has moved to group maintanance.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

MAINTAINERS

@@ -16580,7 +16580,7 @@ M:	Miklos Szeredi <miklos@szeredi.hu>
 M:	Amir Goldstein <amir73il@gmail.com>
 L:	linux-unionfs@vger.kernel.org
 S:	Supported
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs.git
 F:	Documentation/filesystems/overlayfs.rst
 F:	fs/overlayfs/