Non-English installation page bug

[ghost]

I made a different version in version selection, but it does not change.

[seebz]

It seems some strings are missing in Crowdin.

Example with "Arch Linux" who is :

1. defined in https://github.com/yarnpkg/website/blob/master/_data/i18n/en.yml#L270
2. not found/translatable in Crowdin (https://i18n.yarnpkg.com/translate/yarn/all/en-fr#q=install_os_arch shows "No string to display".)

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(Related to #890 and #914)

[yuta0801]

Are there any updates here?