Add the requirements document (#5)

* Add the first revision of the ROS2 Navigation System requirements document.

Author: Michael Jeronimo

README.md

@@ -1,9 +1,9 @@
 # Navigation2
 
-ROS2 Navigation
+ROS2 Navigation System
 
 # Overview
-The ROS2 Navigation system is the central control system for a robot to autonomously move to a given location on a map. Given a current pose, a map and a destination, the system uses sensor input to localize the robot on the map, generates a plan to reach the destination, and outputs commands to drive a robot to that location. It will also autonomously avoid obstacles and re-plan if needed to bypass them.
+The ROS 2 Navigation System is the control system that enables a robot to autonomously reach a goal state, such as a specific position and orientation relative to a specific map. Given a current pose, a map, and a goal, such as a destination pose, the navigation system generates a plan to reach the goal, and outputs commands to autonomously drive the robot, respecting any safety constraints and avoiding obstacles encountered along the way.
 
 # Contributing
-Currently we are in the design phase, and are accepting input and requirements. To contribute, see the [design README.md](design/README.md)
+We are currently in the requirements analysis phase, and are accepting input and requirements. To contribute, see the [documentation README](doc/README.md).

design/README.md

@@ -0,0 +1,8 @@
+# ROS2 Navigation System Documentation
+This is where the ROS2 Navigation System documentation is being collected and vetted.
+
+# Requirements
+See the [requirements document](requirements/requirements.md) for the current list of requirements.
+
+# Contributing
+To propose additions or changes to the requirements, please file an issue against the requirements document to initiate a discussion of the topic. Then, once the discussion has completed and the group has agreed to move forward on the item, you can submit a pull request and link to the issue.