ci: fix trigger for helm doc update workflow step

[borisrizov-zf]

Summary

The trigger for the helm docs update is very restricted (only when changes in the docs happen). This is a problem as the semantic release bot creates commits and updates the Chart.yaml version in the background. This doesn't trigger the docs update and we diverge with every commit.

Solution

Edit the trigger for the helm docs update so it runs on any push/pull_request

[borisrizov-zf]

Relates to #153 and should fix it.