MAINTAINERS: Direct networking documentation changes to netdev

Networking docs changes go through the networking tree, so patch the
MAINTAINERS file to direct authors to the right place.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -9751,6 +9751,7 @@ F:	include/uapi/linux/net_namespace.h
 F:	tools/testing/selftests/net/
 F:	lib/net_utils.c
 F:	lib/random32.c
+F:	Documentation/networking/
 
 NETWORKING [IPSEC]
 M:	Steffen Klassert <steffen.klassert@secunet.com>