docs: Tidy up entrypoints to the docs

[chrisburr]

No description provided.

[Copilot]

Pull Request Overview

This PR tidies up the documentation navigation and entrypoints by reorganizing the structure and content. The changes simplify the user experience by removing detailed project information, updating navigation labels, and creating clearer entry points for different user types.

• Simplified documentation navigation by removing project consortium information and updating section names
• Enhanced the homepage with better styling and clearer paths for users, administrators, and developers
• Added new administrator documentation entry point with clear guidance for different user types

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
mkdocs.yml	Updates navigation structure, simplifies "DiracX Web" to "Web" and changes "Getting started" to "Logging in"
docs/user/index.md	Enhances user guide introduction with more detailed guidance on getting started
docs/project/index.md	Removes project overview content entirely
docs/project/consortium.md	Removes consortium information and member details
docs/assets/home.html	Redesigns homepage with better styling, clearer navigation paths, and removes comparison table
docs/admin/index.md	Adds new administrator documentation entry point with clear user guidance