Modified the zmq_setsockopt documentation to include the ZMQ_ROUTER_HANDOVER option

AUTHORS

@@ -56,6 +56,7 @@ Kamil Shakirov <kamils80@gmail.com>
 Ken Steele <ken@tilera.com>
 Laurent Alebarde <l.alebarde@free.fr>
 Marc Rossi <mrossi19@gmail.com>
+Mark Barbisan <mark.barbisan@evault.com>
 Martin Hurton <hurtonm@gmail.com>
 Martin Lucina <martin@lucina.net>
 Martin Pales <m.pales@gmail.com>

doc/zmq_setsockopt.txt

@@ -13,9 +13,9 @@ SYNOPSIS
 *int zmq_setsockopt (void '*socket', int 'option_name', const void '*option_value', size_t 'option_len');*
 
 Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE,
-ZMQ_LINGER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER, ZMQ_XPUB_VERBOSE,
-ZMQ_REQ_CORRELATE, and ZMQ_REQ_RELAXED, only take effect for subsequent socket
-bind/connects.
+ZMQ_LINGER, ZMQ_ROUTER_HANDOVER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER, 
+ZMQ_XPUB_VERBOSE, ZMQ_REQ_CORRELATE, and ZMQ_REQ_RELAXED, only take effect for 
+subsequent socket bind/connects.
 
 Specifically, security options take effect for subsequent bind/connect calls,
 and can be changed at any time to affect subsequent binds and/or connects.
@@ -393,6 +393,22 @@ Option value unit:: boolean
 Default value:: 0 (false)
 Applicable socket types:: all, only for connection-oriented transports.
 
+ZMQ_ROUTER_HANDOVER: handle peer identity name collisions on ROUTER sockets
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sets the ROUTER socket behavior when it encounters peers with the same identity.
+By default, if two peers with the same identity connect to the same ROUTER 
+socket the results will be undefined. A value of `1` will cause the ROUTER 
+socket to reassign the identity upon encountering an identity name collision.
+Specifically, the first peer to connect with that identity will be terminated
+and the second peer will receive any subsequent messages routed to that 
+identity.
+
+Option value type:: int
+Option value unit:: 0, 1
+Default value:: 0
+Applicable socket types:: ZMQ_ROUTER
+
 
 ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~