#999 fix broken link

Author: valentinsulzer

README.md

@@ -42,9 +42,9 @@ For new users we recommend the [Getting Started](examples/notebooks/Getting%20St
 
 Further details can be found in a number of [detailed examples](examples/notebooks/README.md), hosted here on
 github. In addition, there is a [full API documentation](http://pybamm.readthedocs.io/),
-hosted on [Read The Docs](readthedocs.io). A set of slides giving an overview of PyBaMM
-can be found
-[here](https://github.com/pybamm-team/pybamm_summary_slides/blob/master/pybamm.pdf).
+hosted on [Read The Docs](readthedocs.io). 
+Additional supporting material can be found
+[here](https://github.com/pybamm-team/pybamm-supporting-material/).
 
 For further examples, see the list of repositories that use PyBaMM [here](https://github.com/pybamm-team/pybamm-example-results)