docs: Make german and spanish readme link to the same set of languages as the english readme

[chocoladisco]

Description

I was reading the docs in german and in english and then noticed that in the german version there are less language links than in the english version. As such I fixed it for both german and spanish, as I speak these languages.

closes #1251

Contribution Checklist:

• The pull request only addresses one issue or adds one feature.
• The pull request does not introduce any breaking changes
• I have added screenshots or gifs to help explain the change if applicable.
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

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[chocoladisco]

Screenshot of the languages in the english readme:

Screenshot of the languages in the german readme:

analogous in the spanish readme

[helloanoop]

Thank you @chocoladisco !