🌐 Add Japanese tranlsation for `docs/ja/docs/tutorial/schema-extra-example.md` (#1931)
Co-authored-by: ryusuke.miyaji <bluce826@gmail.com>
Co-authored-by: ryuckel <36391432+ryuckel@users.noreply.github.com>
Co-authored-by: tokusumi <tksmtoms@gmail.com>
Co-authored-by: T. Tokusumi <41147016+tokusumi@users.noreply.github.com>
Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>
