Feature: Add a helm chart for use in k8s

[s0ko1ex]

Hi @tarampampam, thank you for the useful service! I'd like to add files for a helm chart to conveniently deploy your service in Kubernetes clusters and test webhooks from inside them, which can make life easier for many folks like me.

[tarampampam]

Hi there @s0ko1ex!

First of all, I want to sincerely thank you for motivating me to deepen my knowledge of Kubernetes far beyond what I knew before. This is the main reason your PR hasn't been merged yet. To gain more experience, I attempted to create a Helm chart for this app on my own.

Your solution is well-crafted, but I found a few areas that could be improved, and I believe I have successfully made those enhancements (though I'm not entirely sure—but I'd like to think so!).

Could you review my changes in #630? If you find them useful, we can merge them. Otherwise, we can revisit your PR and work on improving it further. What do you think?

[tarampampam]

Merged & released