Add state.state_update documentation and refactor

[jwaa]

Is your feature request related to a problem? Please describe.
The State.state_update method is not documented, and the naming is confusing. Does this mean that the state is updated? Does it return some updated version of the state? Or can one use it to update the state?

Describe the solution you would like
Add the documentation of this method and refactor it to something as State.update_entire_state_with_dict.

Describe alternatives you have considered
N/A

Additional context
Found in the WP3 Multi-Team RVO HAT project.