README files for Helm charts are generated using helm-docs.
Each chart should contain a README.md.gotmpl file that describes how
the README.md of the chart should be generated.
Normally, this file can be the same as the primary template in [docs/templates/README.md.gotmpl] or a symlink pointing to it:
cd charts/CHART
ln -s ../../docs/templates/README.md.gotmplCopy the file to the chart directory if you want to customize the template.
Note: Don't forget to add README.md.gotmpl to .helmignore.
Then run make docs in the repository root.