typo fix

Author: icyblade

README

@@ -10,7 +10,7 @@ Build steps:
 	cmake ..
 	sudo make -j4 install
 
-2) Build cppzmq via cmake. This does an out source build and installs the build files
+2) Build cppzmq via cmake. This does an out of source build and installs the build files
 	download and unzip the lib, cd to directory
 	mkdir build
 	cd build