docs: add Japanese README
I created Japanese translated README.
refs: https://github.com/CVHub520/X-AnyLabeling/pull/468
@eltociear Thank you for your contribution and effort in translating the README into Japanese. We appreciate your initiative. However, please note that the current README.md is not yet finalized and is considered a legacy version. We are working on releasing a new and improved version within the next couple of weeks. Once the updated version is released, we would be more than happy to receive your translation that is tailored to the new content. Please wait for the new version to be published before submitting your translation.
Thank you for your patience and understanding.