[ja] Broken table rendering on "GitHub language support"

### Code of Conduct

- [x] I have read and agree to the GitHub Docs project's [Code of Conduct](https://github.com/github/docs/blob/main/.github/CODE_OF_CONDUCT.md)

### What article on docs.github.com is affected?

https://docs.github.com/ja/get-started/learning-about-github/github-language-support

### What changes are you suggesting?

The language support table is displayed as raw Markdown text, including pipe characters and the separator row, instead of a table.

The equivalent English page renders correctly: https://docs.github.com/en/get-started/learning-about-github/github-language-support

Expected behavior: The Japanese page should render the language support matrix as a table.

### Additional information

_No response_

Start by comparing the Japanese page at docs.github.com/ja/get-started/learning-about-github/github-language-support with the equivalent English page. Inspect the localized source for the language support matrix and how its Markdown differs from the working English version. Done means the Japanese page renders the matrix as a table rather than raw Markdown, with the relevant documentation checks passing.

索引モデルが issue の本文から書いたものです。