zmq_poll man page fixed to reflect the precise timeout semantics.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

doc/zmq_poll.txt

@@ -44,7 +44,7 @@ member, and then indicate any requested events that have occured by setting the
 bit corresponding to the event condition in the 'revents' member.
 
 If none of the requested events have occured on any *zmq_pollitem_t* item,
-_zmq_poll()_ shall wait up to 'timeout' microseconds for an event to occur on
+_zmq_poll()_ shall wait 'timeout' microseconds for an event to occur on
 any of the requested items. If the value of 'timeout' is `0`, _zmq_poll()_
 shall return immediately. If the value of 'timeout' is `-1`, _zmq_poll()_ shall
 block indefinitely until a requested event has occured on at least one
@@ -84,15 +84,9 @@ of *zmq_pollitem_t* structures with events signaled in 'revents' or `0` if no
 events have been signaled. Upon failure, _zmq_poll()_ shall return `-1` and set
 'errno' to one of the values defined below.
 
-IMPORTANT: The _zmq_poll()_ function may return *before* the 'timeout' period
-has expired even if no events have been signaled.
-
 
 ERRORS
 ------
-*EFAULT*::
-At least one of the members of the 'items' array refers to a 'socket' belonging
-to a different application thread.
 *ETERM*::
 At least one of the members of the 'items' array refers to a 'socket' whose
 associated 0MQ 'context' was terminated.