Retooled source path of prometheus.yaml bind mount to reflect an abso…

[FlickRare]

Pull Request

Hello, in Server Monitoring // Prometheus and Grafana Tutorial (Sep 21, 2021) Christian prescribes creating the /etc/prometheus directory to store the prometheus.yaml config file.

As of today, the boilerplate repository specifies the prometheus.yaml bind mount source path as ./config/prometheus.yaml

I feel this introduces two problems as config/prometheus.yaml is now incongruent with the guide and using ./ (relative path) gave me issues too. Using / (absolute path) seems like the more reliable option.

If the repo team would like to keep /config/prometheus.ymal or etc/prometheus/config/prometheus.yaml, I can go in that direction and include a read.me for future users.

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