Add CHANGELOG and Update Documents

Based on [Changelog Strategy doc](https://docs.google.com/document/d/1SFe3ffSJaH18pePc7cqIkMq_uzeSD6uGQe7YkQDy1FQ/edit?pli=1&tab=t.0#heading=h.w701hboahwkj), and https://github.com/IQSS/dataverse-frontend/issues/804 , we discussed on the frontend meeting Sep11th 2025, we decide to move forward and create an issue to add CHANGELOG to the js-dataverse repo.