Docs: Update ACLs on file formats

[Haarolean]

Updated docs on ACLs according to the comment on YAML deprecation

By the way, the 'tests' link is broken and I couldn't find the files this link should mention. Any clues?

• [x] have read the CONTRIBUTING.md file
• [ ] raised a GitHub issue or discussed it on the projects chat beforehand
• [ ] added unit tests
• [ ] added integration tests
• [ ] updated documentation if needed
• [ ] updated CHANGELOG.md

Summary by CodeRabbit

• Documentation
  • Updated Access Control Lists (ACLs) documentation to specify that only huJSON format is accepted, removing the previous YAML option.