Update README.md
fix paths to folders
The Toolbox supports three types of model. Each is represented by a distinct class which inherits from the abstract `Robot` superclass.
-* [Denavit-Hartenberg (DH) models](roboticstoolbox/models/DH). These are defined using standard or modified DH parameters, with optional 3D meshes for visualisation and optional dynamic parameters.
-* [ETS models](roboticstoolbox/models/ETS). There are defined using a sequence of elementary transformations (rotation and translations), and is a quick and intuitive way to describe a robot, see [this article](https://petercorke.com/robotics/a-simple-and-systematic-approach-to-assigning-denavit-hartenberg-parameters/).
-* [URDF models](roboticstoolbox/models/URDF). These models are defined by a Unified Robot Description Format file, an XML format file. Models exist for the classic Puma560 robot as well as the Franka-Emika Panda, the Universal robotics range and all the Interbotix hobby-class robots.
+* [Denavit-Hartenberg (DH) models](https://github.com/petercorke/robotics-toolbox-python/tree/master/roboticstoolbox/models/DH). These are defined using standard or modified DH parameters, with optional 3D meshes for visualisation and optional dynamic parameters.
+* [ETS models](https://github.com/petercorke/robotics-toolbox-python/tree/master/roboticstoolbox/models/ETS). There are defined using a sequence of elementary transformations (rotation and translations), and is a quick and intuitive way to describe a robot, see [this article](https://petercorke.com/robotics/a-simple-and-systematic-approach-to-assigning-denavit-hartenberg-parameters/).
+* [URDF models](https://github.com/petercorke/robotics-toolbox-python/tree/master/roboticstoolbox/models/URDF). These models are defined by a Unified Robot Description Format file, an XML format file. Models exist for the classic Puma560 robot as well as the Franka-Emika Panda, the Universal robotics range and all the Interbotix hobby-class robots.
In each folder you will find a README describing how to create your own model.
