Update or remove docs/configuration.md

[batpad]

The configuration.md in the docs folder seems really out-dated: https://github.com/developmentseed/eoapi-k8s/blob/main/docs/configuration.md

With the presence of values.schema.yaml now, I think we should use that as the source of truth for configuration options.

My preference would be to remove the current outdated configuration.md and then maybe figure out auto-generating something based on the values.schema.yaml?

wdyt @emmanuelmathot @sunu @pantierra ?

[batpad]

I see this is likely covered by #217 - feel free to close if it's not useful to have a separate issue for this.

[emmanuelmathot]

Preliminary tackled in #228 but still to improve for next milestone