Add Japanese version of website pages

[chalin]

• [ja] Localize index page #4580 - adds the ja site landing page
• Add Japanese translation for "What is OpenTelemetry?" #4606
• [ja] Add Japanese translation for getting started #4616
• Create appropriate org-level groups
  • New teams docs-ja-approvers and docs-ja-maintainers community#2138
  • Cf. Create docs-zh-approvers etc #4465
• Update CODEOWNERS
  • Cf. also Create docs-zh-approvers etc #4465 and the PRs used to close it
• [i18n] Initial multilingual support for redirects with ja example #4687

References, previous art, etc:

• Improved i18n support #4467
• Add Chinese version of website #2402

/cc @ymotongpoo

[chalin]

@ymotongpoo @katzchang - note the addition of the Specs section under /ja/docs via:

• [i18n] Initial multilingual support for redirects with ja example #4687

That Specs page is actually just a redirect to the English Specs section (hence the arrow icon next to the section name).

[ymotongpoo]

@chalin thanks for the update. I confirmed the URL of specs pages in Japanese was redirected to the original English version as no Japanese page exists yet.

[chalin]

@open-telemetry/docs-ja-approvers - Closing. Comment here if you feel that there is more core work to be done in the context of this issue — beyond just adding more content.