Add Japanese translation for "What is OpenTelemetry?"

[ymotongpoo]

Docs PR Checklist

• This PR is for a documentation page whose authoritative copy is in the
  opentelemetry.io repository.

---

Preview: https://deploy-preview-4606--opentelemetry.netlify.app/ja/docs/

[ymotongpoo]

@chalin May I ask a quick question? This PR failed because of a missing target.

> __check:links
> make --keep-going check-links

rm -Rf tmp/bin
curl https://htmltest.wjdp.uk | bash -s -- -b tmp/bin
mkdir -p tmp/.htmltest
cp static/refcache.json tmp/.htmltest/
tmp/bin/htmltest --log-level 1
htmltest started at 02:48:47 on public
========================================================================
running in concurrent mode, this is experimental
ja/docs/index.html
  target does not exist --- ja/docs/index.html --> concepts/observability-primer/#what-is-observability
========================================================================
✘✘✘ failed in 1m2.997326825s
1 errors in [87](https://github.com/open-telemetry/opentelemetry.io/actions/runs/9394342440/job/25871928540?pr=4606#step:4:88)6 documents
cp tmp/.htmltest/refcache.json static/
npm run _prettier:any -- --write static/refcache.json

Is this something that #4599 helps?

[ymotongpoo]

@svrnm oh, I did change the path unexpectedly. Thank you for catching the cause!

[chalin]

Thanks all. I have some meetings now, but will come back to this PR. I noticed a few things but don't have time to comment more fully yet, so I've marked this as draft in the meantime.

[chalin]

✨

[chalin]

LGTM
FYI, I'll setup fallback pages in a followup PR.

[chalin]

@ymotongpoo - note the default_lang_commit fields added to the pages of this PR via:

• https://github.com/open-telemetry/opentelemetry.io/pull/4620/files

[ymotongpoo]

Thank you @chalin for merging and sharing the commit that adds a revision snapshot of my translation. Can I assume the following PRs will get similar additions by the automated scripts or do I need to add that metadata by myself?

[chalin]

Hi @ymotongpoo - the GitHub action only checks whether you've added the necessary commit hash. You'll need to add them yourself based on your knowledge of the commit hash of the English language version of the page(s) you are translating -- which might not be at main@HEAD.

If you are working from en pages @HEAD then you can run the script mention in https://opentelemetry.io/docs/contributing/localization/#adding-default_lang_commit-to-new-pages.

[ymotongpoo]

Thank you @chalin for clarifying the process. Then I will add the revisions in the upcoming PRs.