[NET]: bonding documentation fix for multiple bonding interfaces

Fix bonding driver documentation for the case of multiple bonding interfaces.

Signed-off-by: "Alexandra N. Kossovsky" <Alexandra.Kossovsky@oktetlabs.ru>
Acked-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>