add freq-coupling to examples list

Author: lazyoracle

README.md

@@ -48,6 +48,7 @@ The following notebooks are available in the `examples/` directory and can also
 - [Minimum example for using the Qiskit interface](examples/c3_qiskit.ipynb)
 - [Minimum example for optimizing piece-wise constant pulses](examples/Piecewise_constant_controls.ipynb)
 - [Understanding the ParameterMap](examples/Parametermap.ipynb)
+- [Frequency Dependent Coupling](examples/frequency_dependent_coupling.ipynb)
 
 ## Contributing
 
@@ -70,4 +71,4 @@ If you use `c3-toolset` in your research, please cite it as below:
    year={2021},
    month={Mar}
 }
-```
+```