Document Restore/SaveGameDialog in Globalfunctions_General

[ericoporto]

https://github.com/adventuregamestudio/ags-manual/wiki/Globalfunctions_General#restoregamedialog

RestoreGameDialog() and SaveGameDialog() now let define a range of save slots for display.

The min_slot and max_slot parameters are new to 3.6.2 release

/// Displays the default built-in Restore Game dialog.
import void RestoreGameDialog(int min_slot = 1, int max_slot = 100);
/// Displays the default built-in Save Game dialog.
import void SaveGameDialog(int min_slot = 1, int max_slot = 100);

Added also in PR adventuregamestudio/ags#2541

[ericoporto]

Added in https://github.com/adventuregamestudio/ags-manual/wiki/Globalfunctions_General/_compare/679f75230d23e473f8bdadd2be0ad181c9e4be5e...324ea05705255bb97c1c7e5d4573114c7869d09a