Use English for event names

[toshimaru]

Why:

Translations for event names are not needed.
So, use English event names instead of Japanese.

What's being changed:

• Translated headings
• Translated webhook payload names

Before

After

Check off the following:

• All of the tests are passing.
• I have reviewed my changes in staging.
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[zeke]

Thanks for opening this pull request @toshimaru!

Unfortunately, we are not able to accept pull requests for translated content. Our translation process involves an integration with an external service at crowdin.com, where all translation activity happens. We hope to eventually open up the translation process to the open-source community, but we're not there yet. See https://github.com/github/docs/blob/main/CONTRIBUTING.md#earth_asia-translations for more details.

I have opened an issue in our internal localization tracking repo with a link to the changes you've proposed here, and we'll make sure our translators get this fixed soon.

Thanks again!