i18n: Add feedback_* to i18n/ja.toml

[rinsuki]

Context: while reading OpenTelemetry's document, I noticed that their feedback form's i18n is completely broken in Japanese:

(Screenshot of https://opentelemetry.io/ja/docs/ )

and after some research, I think it was from docsy, not opentelemetry.io's fault, then I just made this patch.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[chalin]

Thank you @rinsuki, I've asked https://github.com/orgs/open-telemetry/teams/docs-ja-maintainers to review and comment.

[chalin]

LGTM. Will give OTel docs-ja-maintainers some time to give feedback.

[deining]

Just realized that there are some more untranslated lines/strings in this file:

https://github.com/google/docsy/blob/fa81a86be8bf130d94a43b8898c6716819fdae87/i18n/ja.toml#L63C1-L79C34

@rinsuki: are you able to translate these lines as well? Your help is appreciated!

[rinsuki]

technically I can directly translate word-by-word, but I think it wouldn't be a good translate (If I do that, japanese speakers (like me) feels it is translated from other language rather than written by native), but I don't have a idea to good paraphrase for its text right now.

by the way, community_how_to assume text ends with community_guideline:

docsy/layouts/partials/community_links.html

Lines 18 to 21 in fa81a86

	<p>
	{{ T "community_how_to" . }}
	<a href="{{ $contribUrl | relURL }}">{{ T "community_guideline" }}</a>.
	</p>

but some languages wants to have additional text after link, it would be good to have something like community_how_to_suffix.

[chalin]

Ok, thanks @rinsuki. I'll merge this as an increment, and we can address the other fields as necessary. Thanks for pointing that out @deining.

[ymotongpoo]

@chalin Do you need Japanese speakers review? (it seems https://github.com/orgs/open-telemetry/teams/docs-ja-maintainers consists of non-Japanese speakers. Asking just in case.)

If yes, the content looks good to me. (btw, https://github.com/orgs/open-telemetry/teams/docs-ja-approvers is docs-ja-maintainers + me and @katzchang)

[chalin]

@chalin Do you need Japanese speakers review? (it seems https://github.com/orgs/open-telemetry/teams/docs-ja-maintainers consists of non-Japanese speakers. Asking just in case.)

Oh! Yes, that was my intention.

If yes, the content looks good to me.

Thank you for validating.

(btw, https://github.com/orgs/open-telemetry/teams/docs-ja-approvers is docs-ja-maintainers + me and @katzchang)

Got it, thanks.