add setup instructions on README.md (#43)

* add setup instructions on README.md

README.md

@@ -5,3 +5,54 @@
 NoDL is the Node Definition Language - a common declarative representation of a Node's interfaces including Parameters, Topics, Services, and Actions. See the [design document (review in progress)](https://github.com/ubuntu-robotics/design/blob/node_idl/articles/ros2_nodl.md) for more context on the project.
 
 This repository contains the CLI and parsing utilities for NoDL.
+
+## Installation
+
+Run `python3 setup.py install`
+
+Install the 'ament_nodl' extension for exporting NoDL .xml files:
+
+`sudo apt-get install ros-<ros2_distro>-ament-nodl`
+
+## Configuration
+
+Add to `package.xml`:
+
+`<depend>ament_nodl</depend>`
+
+Add to `CMakeLists.txt`:
+
+`find_package(ament_nodl REQUIRED)`
+
+`nodl_export_node_description_file(<package_name>.nodl.xml)`
+
+## Usage
+
+Create a file called "<package_name>.nodl.xml" in the same folder as your project's CMakeLists.txt. 
+Include in this file the interface description for each node in the package.
+Node attributes can be `parameter`, `topic`, `service` or `action`.
+
+Valid values for the topic `role` tag are: `publisher`, `subscription`, or `both`.
+Valid values for the service `role` tag are: `server`, `client`, or `both`.
+Valid values for the action `role` tag are: `server`, `client`, or `both`.
+Types can have custom names.
+
+### Example
+
+```xml
+<interface version="1">
+	<node name="<node1_name>" executable="<executable_name>">
+		<parameter name="rate" type="int" />
+		<topic name="/foo/bar" type="std_msgs/msg/String" role="subscription" />
+		<service name="/example_service" type="std_srvs/srv/Empty" role="client" />
+		<action name="/example_action" type="example_interfaces/action/Fibonacci" role="both" />
+	</node>
+	<node name="<node2_name>" executable="<executable_name>">
+		...
+	</node>
+</interface>
+```
+
+## CLI
+
+See available verbs on the [ROS 2 command line tools for NoDL repo](https://github.com/ubuntu-robotics/nodl/tree/master/ros2nodl).