fix: url version slugs

[AlexAndBear]

The version in the url slug was missing, which will make versioning of the docs even harder as soon we will publish docs for the next release.

Version 4
https://docs.opencloud.eu/docs/user/intro -> https://docs.opencloud.eu/docs/4.0/user/intro

Rolling
https://docs.opencloud.eu/docs/next/user/intro -> https://docs.opencloud.eu/docs/user/intro
this will keep existing links to docs intact

[AlexAndBear]

FYI @micbar

[Copilot]

Pull request overview

This PR implements versioning in documentation URL slugs to improve version management and maintainability. The changes ensure that version 4.0 documentation is accessible at a versioned path (/docs/4.0/...) while the rolling/current version remains at the base path (/docs/...), preserving existing links.

Changes:

• Added URL path configuration for documentation versions in Docusaurus config
• Created English translation file for version 4.0 with comprehensive sidebar and category labels
• Updated German translation file to align version description with the stable-4.0 identifier

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docusaurus.config.ts	Configured version paths: current version at base path, stable-4.0 at /4.0 path
i18n/en/docusaurus-plugin-content-docs/version-stable-4.0.json	Added complete English translations for version 4.0 documentation structure
i18n/de/docusaurus-plugin-content-docs/version-stable-4.0.json	Updated version description to match stable-4.0 identifier

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[AlexAndBear]

@Svanvith It looks like you need to adjust a ton of urls :sigh:

when we e.G use the link

[Manage Files and Folders](/docs/user/files-and-folders)

this will not keep the version slug in the url looks like we need to use the relative urls again

e.G ./files-and-folders

Can you please adjust this PR

[AlexAndBear]

I am not quite sure anymore.

Let's discuss this when I am back from vacation