osx build notes: libzmq -> zmq in brew install, add libevent

Author: tofutim

doc/build-osx.md

@@ -38,7 +38,7 @@ Instructions: Homebrew
 
 #### Install dependencies using Homebrew
 
-        brew install autoconf automake berkeley-db4 libtool boost miniupnpc openssl pkg-config protobuf qt5 libzmq
+        brew install autoconf automake berkeley-db4 libtool boost miniupnpc openssl pkg-config protobuf qt5 zmq libevent
 
 ### Building `pivxd`