Merge pull request #3422 from sigiesec/fix-zmq-proxy-docs

Problem: zmq_proxy signature in documentation does not match actual s…

doc/zmq_proxy.txt

@@ -8,7 +8,7 @@ zmq_proxy - start built-in 0MQ proxy
 
 SYNOPSIS
 --------
-*int zmq_proxy (const void '*frontend', const void '*backend', const void '*capture');*
+*int zmq_proxy (void '*frontend', void '*backend', void '*capture');*
 
 
 DESCRIPTION