MAINTAINERS: Add BATMAN ADVANCED documentation files

The sysfs ABI documentation files and the batman-adv.txt are maintained by
the BATMAN ADVANCED maintainers and patches for them should therefore be
sent to them.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Antonio Quartulli <a@unstable.cc>

MAINTAINERS

@@ -2207,6 +2207,9 @@ L:	b.a.t.m.a.n@lists.open-mesh.org (moderated for non-subscribers)
 W:	https://www.open-mesh.org/
 Q:	https://patchwork.open-mesh.org/project/batman/list/
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-class-net-batman-adv
+F:	Documentation/ABI/testing/sysfs-class-net-mesh
+F:	Documentation/networking/batman-adv.txt
 F:	net/batman-adv/
 
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