add link in readme

Signed-off-by: Coline PILOQUET <coline.piloquet@rte-france.com>

Author: colineplqt

README.md

@@ -9,4 +9,5 @@
 - Computation using Dynaflow : [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/powsybl/pypowsybl-notebooks/main?labpath=dynaflow/pypowsybl_dynaflow.ipynb)
 - Sensitivity analysis and PTDF calculation [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/powsybl/pypowsybl-notebooks/main?labpath=sensitivity_analysis.ipynb)
 - Pypowsybl-Jupyter widgets notebook : [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/powsybl/pypowsybl-notebooks/main?labpath=pypowsybl_jupyter_widgets_demo.ipynb)
+- Open-RAO notebook : [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/powsybl/pypowsybl-notebooks/main?labpath=open_rao.ipynb)