Ensure helm chart README.md's are in sync with the go-template

[florianrusch-zf]

Is your feature request related to a problem? Please describe.
Currently if someone updates the go-template for our helm charts we don't have any automatism that performs the generation of the README.md files. This is therefore a manual step that could be forgotten or where typos can happen.

Describe the solution you'd like
Add a CI job that checks if both files are in sync with each other.

Describe alternatives you've considered
Automate the creation of the README.md files, but for that the question would be when do we want to do that 🤔 (see discussion in the linked PR below)

Additional context
Was discover in PR #261