add a definition for ROS2

docs/source/common_jargon.md

@@ -3,6 +3,10 @@
 | Component / Word  | Definition  | Link to learn more|
 | :---------------- | :---------- | :---------------- |
 | Motor | when we say this we are normally talking about a DC brushed motor which spins when you apply power to it | [Haven't seen](https://www.youtube.com/watch?v=onjFFoOC_yk)
+| ROS 2 | ROS is an open source robotics middleware | [ROS tutorials](https://docs.ros.org/en/humble/Tutorials.html)
+
+
+