Fix typos and change .provides. -> ._. in readme

[esselius]

Really excited about this project but the readme debt confused me :)

Working on similar PRs for flake-file, flake-aspects and vix

[Copilot]

Pull Request Overview

This PR updates the README documentation to fix several typos and standardize terminology around the _ accessor (alias for provides).

• Fixed spelling errors including "Aditional" → "Additional" and duplicate "host" → "home"
• Updated code examples and text to consistently use den._ instead of den.provides
• Corrected method name typo from include to includes

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[vic]

Thank you so much! Definitely prose and documentation is as important as code, thanks for taking the time to fix my typos. I tend to write in a hurry, will try to get better at my English prose.

Thank you again!