Documentation: Improve history documentation

Is your feature request related to a problem? Please describe. Documentation seems to mention how to enable the history button (and even mention how to make a custom history button, although I couldn't get the latter to work properly: despite calling the function it should call according to the documentation, it didn't trigger the history screen, and clicking it also advanced the dialogue which is probably a bug). But it doesn't say much about changing the "history state" or whatever it's called. If you reach the end of a game and start over from the main menu without closing and reopening the game, perhaps you don't want messages the previous playthrough to show up when you click the history button during the new playthrough. And I haven't tested saving and loading so far, but I'd hope it's be possible to restore a previous playthrough's history state when loading a savegame from it (wouldn't really be a bug if it wasn't, but Ren'Py does that automatically, and I wouldn't think players wouldn't expect that in other engines).

Describe the solution you'd like The documentation explaining how to reset the history, and/or how to load it with a previously captured state.

Describe alternatives you've considered Perhaps make an example game that does this, then at least people looking at how that game works can do what it does. An example game can also be useful for testing, since if you change something in the engine that would require a change in the example game, testing the example game might be quicker than reading through the entire documentation to make sure nothing there needs to be changed.

Additional context I'm probably more familiar with Ren'Py than Dialogic, but I do have some more experience with Godot, including having made a VN in Godot before (where I didn't use Dialogic).

[Edit: I was using Dialogic 2. Sorry for forgetting to mention that.]

dialogic-godot / documentation

Documentation: Improve history documentation #40