MAINTAINERS: add missing qcow2 entry

Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

MAINTAINERS

@@ -1872,6 +1872,7 @@ M: Max Reitz <mreitz@redhat.com>
 L: qemu-block@nongnu.org
 S: Supported
 F: block/qcow2*
+F: docs/interop/qcow2.txt
 
 qcow
 M: Kevin Wolf <kwolf@redhat.com>