Problem: UDP is not mentioned in bind and connect

zmq_bind(3) and zmq_connect(3) does not mention UDP as available
transport types.

Solution: add udp mentioning line for related docs

doc/zmq_bind.txt

@@ -28,6 +28,7 @@ The 'endpoint' is a string consisting of a 'transport'`://` followed by an
 'inproc':: local in-process (inter-thread) communication transport, see linkzmq:zmq_inproc[7]
 'pgm', 'epgm':: reliable multicast transport using PGM, see linkzmq:zmq_pgm[7]
 'vmci':: virtual machine communications interface (VMCI), see linkzmq:zmq_vmci[7]
+'udp':: unreliable unicast and multicast using UDP, see linkzmq:zmq_udp[7]
 
 Every 0MQ socket type except 'ZMQ_PAIR' supports one-to-many and many-to-one
 semantics. The precise semantics depend on the socket type and are defined in

doc/zmq_connect.txt

@@ -28,6 +28,7 @@ The 'endpoint' is a string consisting of a 'transport'`://` followed by an
 'inproc':: local in-process (inter-thread) communication transport, see linkzmq:zmq_inproc[7]
 'pgm', 'epgm':: reliable multicast transport using PGM, see linkzmq:zmq_pgm[7]
 'vmci':: virtual machine communications interface (VMCI), see linkzmq:zmq_vmci[7]
+'udp':: unreliable unicast and multicast using UDP, see linkzmq:zmq_udp[7]
 
 Every 0MQ socket type except 'ZMQ_PAIR' supports one-to-many and many-to-one
 semantics. The precise semantics depend on the socket type and are defined in