Update outdated URL in README.md

[Y-Kim-64]

Summary:

• Replaced outdated URL in the README.md file with the new one.

Details:

• During my review of the README.md file, I noticed that one of the URLs was outdated and led to a 404 page. This PR updates the URL to point to the correct resource, ensuring that users and contributors have access to accurate and up-to-date information.

Testing:

• Clicked on the updated URL to ensure it directs to the correct page.
• Checked the formatting of the README.md file to ensure the change doesn't affect the overall layout.

Impact:

• This change will ensure that users and contributors are directed to the correct resource, enhancing the user experience and credibility of the repository.

Suggestions for further improvements:

• Regularly audit external links in the repository to ensure they remain up-to-date.
• Consider using tools or GitHub Actions that automatically check for broken links in markdown files.

Thank you for considering this PR. I'm open to any feedback or changes you'd like to see before merging.

[Y-Kim-64]

Hello Maintainers,

I've updated the README.md with a URL that connects to the 'Tor Rendezvous Specification - Version 3'. However, I'd like to bring to your attention an alternative link that points to a plain-text version of the specification on the Tor Project's official GitLab repository: rend-spec-v3.txt.

This plain-text version might be useful for certain users or use cases. It could be considered for inclusion in the repository, either as an alternative or supplementary link.

Thank you for your consideration.

[cathugger]

Thanks!

Link you've used seems to be an authoritative source, and gitlab one seems to be closest to what I've based this on.
Maybe if we use actual footnotes¹ we could do both.

Footnotes

1. https://github.blog/changelog/2021-09-30-footnotes-now-supported-in-markdown-fields/ ↩