📝(doc) add Federated Nexus docs instance

[Henry-Hiles]

Purpose

Adds a new Docs instance, as suggested here: #1316

External contributions

Thank you for your contribution! 🎉

Please ensure the following items are checked before submitting your pull request:

• I have read and followed the contributing guidelines
• I have read and agreed to the Code of Conduct
• I have signed off my commits with git commit --signoff (DCO compliance)
• I have signed my commits with my SSH or GPG key (git commit -S)
• My commit messages follow the required format: <gitmoji>(type) title description
• I have added a changelog entry under ## [Unreleased] section (if noticeable change)
• I have added corresponding tests for new features or bug fixes (if applicable)

[Henry-Hiles]

I wasn't sure if I had to signoff and everything for something as simple as this, but I can clone it locally to do that if needed.

[virgile-dev]

Hey, @Henry-Hiles
Thanks for adding you url and hosting an open instance of Docs !
yes you do need to sign off all changes are subject to it and the CI won’t pass haha

[Henry-Hiles]

Hey, @Henry-Hiles Thanks for adding you url and hosting an open instance of Docs ! yes you do need to sign off all changes are subject to it and the CI won’t pass haha

Alrighty, I've signed off.