Documentation pages for Setup (Linux, Windows, macOS) are empty on ReadTheDocs

Hi team,
I noticed that several documentation pages in the EvalAI ReadTheDocs site appear to be incomplete or completely empty.

### Affected Pages

These pages currently show only a title but no actual content:

* **Docker Setup**
* **Linux Setup**
* **Windows Setup**
* **macOS Setup**
* Possibly other pages under **Getting Started → Setup**

### Issue Summary

The pages are visible in the sidebar, but when opened they appear to contain only:

* Page title
* Empty body
* Navigation buttons ("Previous" / "Next")

This seems like either:

* The `.rst` files exist but are empty
* The content was not added to the Sphinx build
* The pages are placeholders that were never completed
* They were mistakenly excluded from the documentation build

### Impact

* New contributors cannot properly set up EvalAI on their systems.
* The hosts and developers following the docs may face confusion.
* This reduces usability and onboarding for the project.

### Suggestion

* Verify if the corresponding `.rst` files exist under `docs/source/`
* Add missing content or hide these pages until they are properly documented
* (If helpful) I’m willing to contribute and help improve the documentation once the expected structure or missing details are clarified.
* And finally I can solve this issue early.

---

If you want, I can also help you **create a PR after this issue is opened**.

Inspect the documentation files under docs/source/ for Docker, Linux, Windows, and macOS Setup, then check how the Getting Started → Setup pages are included in the ReadTheDocs/Sphinx build. Verify whether the .rst files are empty or excluded. Done means the affected pages contain the intended setup content or are removed from navigation until documented.

Written by the indexing model from the issue text.