Fix README.md file and add rbac.yaml description

[michael34435]

I’ve modified README file and add some descriptions

[googlebot]

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[michael34435]

I signed it!

[googlebot]

CLAs look good, thanks!

[krzykwas]

Hello! Thank you for spotting and fixing the errors. Because of the way the code of this project is developed right now, this pull request unfortunately cannot be directly merged - the code is developed in an internal repository and then only pushed here. I've fixed the errors you've found, though. Thank you!