docs(README): Update release badges & ClusterRole aggregation

[doronkg]

What this PR does / why we need it?

This PR adds 2 small fixes to README.md:

1. Adds discovery reference for ClusterRole aggregation (added in #221).
2. Separates release badges for kor & Helm.

Current: Updated:

PR Checklist

• [ ] This PR adds K8s exceptions (false positives)
• [ ] This PR adds new code
• [ ] This PR includes tests for new/existing code
• [x] This PR adds docs

Notes for your reviewers

I used https://shields.io/badges/git-hub-release to test the badges.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 42.39%. Comparing base (01ce4a6) to head (1a35afc). Report is 4 commits behind head on main.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #340 +/- ## ======================================= Coverage 42.39% 42.39% ======================================= Files 61 61 Lines 3236 3236 ======================================= Hits 1372 1372 Misses 1644 1644 Partials 220 220 ```

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