Fix dead links referring to powsybl.org. (#376)

Signed-off-by: Coline PILOQUET <[email protected]>

README.md

@@ -7,7 +7,7 @@
 [![Javadocs](https://www.javadoc.io/badge/com.powsybl/powsybl-dynawo.svg?color=blue)](https://www.javadoc.io/doc/com.powsybl/powsybl-dynawo)
 [![Slack](https://img.shields.io/badge/slack-powsybl-blueviolet.svg?logo=slack)](https://join.slack.com/t/powsybl/shared_invite/zt-rzvbuzjk-nxi0boim1RKPS5PjieI0rA)
 
-[Dynawo](https://dynawo.github.io) is an hybrid C++/Modelica open source suite of simulation tools for power systems. This integration module allows to use [DynaFlow](https://dynawo.github.io/about/dynaflow) for [power flow simulations](https://www.powsybl.org/pages/documentation/simulation/powerflow) and [Dynawo](https://dynawo.github.io) for [time domain simulations](https://www.powsybl.org/pages/documentation/simulation/timedomain).
+[Dynawo](https://dynawo.github.io) is an hybrid C++/Modelica open source suite of simulation tools for power systems. This integration module allows to use [DynaFlow](https://dynawo.github.io/about/dynaflow) for [power flow simulations](https://powsybl.readthedocs.io/projects/powsybl-core/en/stable/simulation/loadflow/index.html) and [Dynawo](https://dynawo.github.io) for [time domain simulations](https://powsybl.readthedocs.io/projects/powsybl-core/en/stable/simulation/dynamic/index.html).
 
 ## DynaFlow
 
@@ -19,7 +19,7 @@ LoadFlowParameters parameters = LoadFlowParameters.load();
 LoadFlow.find("DynaFlow").run(network, parameters);
 ```
 
-To learn more about the usage of DynaFlow, read the [dedicated page](https://www.powsybl.org/pages/documentation/simulation/powerflow/dynaflow.html) on our website.
+To learn more about the usage of DynaFlow, read the [dedicated page](https://powsybl.readthedocs.io/projects/powsybl-dynawo/en/latest/load_flow/index.html) on our website.
 
 ## Dynawo
 
@@ -62,7 +62,7 @@ System.out.println("Timeline:");
 result.getTimeLine().forEach(tl -> System.out.printf("[%.8f] %s (on %s)%n", tl.time(), tl.message(), tl.modelName()));
 ```
 
-To learn more about the usage of Dynawo, read the [dedicated page](https://www.powsybl.org/pages/documentation/simulation/timedomain/dynawo) on our website.
+To learn more about the usage of Dynawo, read the [dedicated page](https://powsybl.readthedocs.io/projects/powsybl-dynawo/en/latest/dynamic_simulation/index.html) on our website.
 
 ### Examples