Add support for Rocky Linux

[trippsc2]

Proposed changes

Added support for Rocky Linux for this role.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have added Molecule tests that prove my fix is effective or that my feature works
• I have checked that any relevant Molecule tests pass after adding my changes
• I have updated any relevant documentation (defaults/main/*.yml, README.md and CHANGELOG.md)

[alessfg]

Heya and thanks for the PR! Sadly, Rocky Linux is not an officially supported distribution as of today. There have been some talks about it, but there's nothing confirmed for the time being. Nonetheless I am going to leave this PR open and if things do change in the future, I will merge it asap 😄

P.S.: The role should work as is on Rocky Linux. If it doesn't, I am happy to make the necessary changes to get it running, but I can't add it to the "officially" supported list of distros unless we actually start supporting (you can check the supported distros at https://nginx.org/en/linux_packages.html).

[alessfg]

Closing in favor of #562 :)