Release: Create a release process for Starship helm charts

[nascentcore-eng]

Right now the release is done for each commit to main branch (and for tags with release-v* pattern, it's 'OR', not 'AND', in other words, every command to main branch triggers a helm chart release).

We just moved README.md copying to gh-pages to the release-charts.yaml workflow. And changes the triggering condition to be on manual trigger by opening github actions tag and launch the workflow.

Ideally, we want auto-tigger by a new tag pushed. Then it just start creating new release on the new tag.

[nascentcore-eng]

To add on the background, currently, without updating version variable in charts/starship/Chart.yaml, the release will fail, as Helm chart release reads the the version and name the new release after the version name.

When trying to post the release artifacts with the version variable, the uploading will fail as there is already a file with the same name: