Update README.md

README.md

@@ -14,3 +14,6 @@ The **MATSim input files, output files, analysis data and visualizations** are l
 <a rel="license" href="http://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by/4.0/80x15.png" /></a><br /> MATSim input files are those that are used as input to run MATSim. They often, but not always, have a header pointing to matsim.org. They typically reside in the `scenarios` directory hierarchy. MATSim output files, analysis data, and visualizations are files generated by MATSim runs, or by postprocessing.  They typically reside in a directory hierarchy starting with `output`.
 
 **Other data files**, in particular in `original-input-data`, have their own individual licenses that need to be individually clarified with the copyright holders.
+
+### Internal Documentation
+See [GoogleDoc](https://docs.google.com/document/d/169le1oRb5Z0V2ICyyu3RoOP9-ZJ1LhKG0EeU-VD1MIU/edit)