CA and certificate logic was simplified in a previous PR, but the README was not updated to reflect latest changes.

What this PR does / why we need it:

Update README

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• Title of the PR starts with type and scope, (e.g. feat(agent,node-analyzer,sysdig-deploy):)
• Chart Version bumped for the respective charts
• Variables are documented in the README.md (or README.tpl in some charts)
• Check GithubAction checks (like lint) to avoid merge-check stoppers
• All test files are added in the tests folder of their respective chart and have a "_test" suffix

Check Contribution guidelines in README.md for more insight.