Added build instructions

Author: kydos

README.md

@@ -21,3 +21,13 @@ this experiment will help the ROS community making ROS 2 even better.
 ## Status
 **ROS-Z** is experimental software. It should be interoperable with ROS 2 Rolling, but we make no guarantees with respect 
 to official distributions.
+
+## Building
+To build ROS-Z without any ROS 2 dependency do:
+
+    $ cargo build -p ros-z
+
+Otherwise if you have ROS 2 installed you can build with:
+
+    $ cargo build 
+