[FEATURE] Allow overwriting jinja template in helm chart

[jonerer]

Description

Hello!

Thanks for the awesome project, it's working really well to help us connect alertmanager to power automate. However, there are a couple of things I would like to do to the template to make it fit our organization better. I'm using the official helm chart https://github.com/idealista/prom2teams/tree/develop/helm , but it doesn't have any way to allow me to overwrite the template file.

Why is this needed?

We want to modify the template. More specifically we want to remove "Prometheus alert" from the header, and prevent it from putting the text "unknown" in the header of most alerts.

Additional Information

Either of these solutions could help us work through the problem:

• Allow a custom volume & volumeMount, then we could mount in our own template and point to it. Bitnami helm charts typically do this.
• Allow an input like "{{ .Values.prom2teams.alertTemplateContent }}", which, if filled, gets inputted into the ConfigMap as the value "teams.j2" here: https://github.com/idealista/prom2teams/blob/develop/helm/templates/configmap.yaml

Thanks in advance