Add dynamic-simulation page

[mathbagu]

• Do you want to request a feature or report a bug?
  Request

• What is the current behavior?
  The documentation of the dynamic-simulation tool doesn't exist.

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

• What is the expected behavior?
  Have a complete documentation of this tool. A link to this new page has to be available from the menu (User documentation section) and from the itools page

• What is the motivation / use case for changing the behavior?
  Be exhaustive

• Please tell us about your environment:

  • PowSyBl Version: 3.1.0
  • OS Version: All

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, spectrum, etc)

(if a question doesn't apply, you can delete it)

[mathbagu]

https://www.powsybl.org/pages/documentation/simulation/timedomain/

@marcosmc I think we report the documentation you wrote in the new website. Could you confirm and close your PR, or rebase your PR onto the master branch?