docs: update README.md

[eltociear]

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

Problem/Feature

Please include a description of the problem or feature this PR is addressing.

Description of Changes:

• Github -> GitHub

Checklist

• I have self-reviewed the changes being requested
• I have updated the documentation (check issue ticket 📋Update documentation if the PR introduces a new feature!📋 #218)

[Ujstor]

Man, I can't accept one letter change. If you want, you can update the README screenshot. The core blueprint added a new database (ScyllaDB), and we forgot to update the CLI screenshots in the docs and README. Check for other possible improvements in the docs, and that PR will be good. Just match the same CLI style and color.