MAINTAINERS: Add headers and mailing list to UDP section

Add netdev mailing list and some more udp.h headers to the UDP section.
This is now more consistent with the TCP section.

Acked-by: Willem de Bruijn <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: horms

MAINTAINERS

@@ -24184,8 +24184,12 @@ F:	drivers/usb/host/xhci*
 
 USER DATAGRAM PROTOCOL (UDP)
 M:	Willem de Bruijn <[email protected]>
+L:	[email protected]
 S:	Maintained
 F:	include/linux/udp.h
+F:	include/net/udp.h
+F:	include/trace/events/udp.h
+F:	include/uapi/linux/udp.h
 F:	net/ipv4/udp.c
 F:	net/ipv6/udp.c