fix(docs): use file-relative .md/.mdx links to prevent URL resolution bugs

[lennardrother]

What this PR does / why we need it:

Fixes broken links by replacing them with releative links with .md/.mdx extension.

The following links were fixed:

• https://open-control-plane.io/users/getting-started — (Onboarding, Connect, Configure, Managed Control Plane, Projects & Workspaces, Service Providers, open-source projects, onboarding guide)
• https://open-control-plane.io/operators/overview — (Quickstart)
• https://open-control-plane.io/operators/production-setup/production-overview — (Gardener Provider)
• https://open-control-plane.io/developers/overview — (how to create a Service Provider)
• https://open-control-plane.io/developers/serviceprovider/develop — (Testing guide, Debug guide)

Example:

Screen.Recording.2026-05-22.at.11.54.39.mov

Which issue(s) this PR fixes:
NONE

Special notes for your reviewer:

Release note:

Fixed broken links by replacing them with releative links with .md/.mdx extension

[maximiliantech]

Hi @lennardrother, thanks for testing this 🥇 I am a bit unsure if we are really solving the URL resolution bugs here. What I do see is that we still have a lot of different file extensions. Some of them being .md and some of them being .mdx. I remember that we have looked into this whole URL resolution and page referencing problem before and we came to the conclusion that we simply use the id field in the header of every file. Shouldn't we use this instead of the file extensions? What do you think?

[lennardrother]

Hi, if I understand correctly setting id doesn't solve the issue.

According to the docs there are two ways of linking: through a URL path (without file extension) or a file path (with file extension). URL paths are resolved according to the page's URL location. This means this link without file extension is rendered as <a href="/users/getting-started/getting-started/onboard">Onboarding</a>, which does not exist. The file lives in users/getting-started and has the id onboard so it is available at /users/getting-started/onboard.

I assume we wanted to link using file path but forgot the extension so Docusaurus uses the URL path.