Update README

[wkonitzer]

Correct some minor errors in the README and add an appendix to install the demo repo on a non-Kind cluster.

[Algeran]

1. Maybe it would be better to add all notes about installing/configuring and cleaning an existing cluster to the separate documentation file in the docs directory and just link it from the README?
2. Please rebase the branch and squash commits to one or several (if it's required) to keep the main branch clean

[wkonitzer]

1. Maybe it would be better to add all notes about installing/configuring and cleaning an existing cluster to the separate documentation file in the docs directory and just link it from the README?
2. Please rebase the branch and squash commits to one or several (if it's required) to keep the main branch clean

OK, Let me do that.

[wkonitzer]

@Algeran All done. Hopefully we can accept the PR.