Update docu

Author: ufechner7

docs/src/advanced.md

@@ -71,6 +71,8 @@ Good: `norm1        ~ norm(segment)`
 ## Outlook
 
 The next steps:
-- re-implement the KPS4 model using ModelingToolkit
+- finish and merge the KPS5 kite power system model, based on ModellingToolkit
+- use VortexStepMethod.jl for KPS5 
+- add a rigid wing model
 - add a Matlab/ Simulink wrapper similar to the Python wrapper [pykitemodels](https://github.com/ufechner7/pykitemodels)