[i18n] Consistently implement the handling of the OTel specs across localizations, and document the solution

[chalin]

Propagate the ja solution to other localizations, and document it under https://opentelemetry.io/docs/contributing/localization.

[ymotongpoo]

reviving this topic. because the spec docs are located in the different repository (https://github.com/open-telemetry/opentelemetry-specification), how do we localize the spec documents? do you already have any ideas for the procedure?