docs: Update codeql-action README to use v2

[Mrtenz]

The README in codeql-action was referencing the wrong repository and outdated options. I've fixed that here.

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Note

Refresh README examples to use the v2 reusable workflow with scanner-ref: v2 and include the minimal GitHub permissions.

• Docs:
  • Root README.md:
    • Add minimal permissions block to the reusable workflow example (actions: read, contents: read, security-events: write).
  • packages/codeql-action/README.md:
    • Update reusable workflow example to MetaMask/action-security-code-scanner/.github/workflows/security-scan.yml@v2 with scanner-ref: v2.
    • Rename job to security-scan and include minimal permissions block.
    • Remove outdated repo input from workflow example.

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