message: doc: Adjust ZMQ usage to support multiple interfaces
diff: @@ -67,6 +67,7 @@ Currently, the following notifications are supported:
  The socket type is PUB and the address must be a valid ZeroMQ socket
  address. The same address can be used in more than one notification.
  +The same notification can be specified more than once.
  The option to set the PUB socket's outbound message high water mark
  (SNDHWM) may be set individually for each notification:
  @@ -82,6 +83,7 @@ The high water mark value must be an integer greater than or equal to 0.
  For instance:
  $ peercoind -zmqpubhashtx=tcp://127.0.0.1:28332 \
  + -zmqpubhashtx=tcp://192.168.1.2:28332 \
  -zmqpubrawtx=ipc:///tmp/peercoind.tx.raw \
  -zmqpubhashtxhwm=10000
  