[Docs] Add docs on automatically starting otel collector on system startup

[pranay01]

I'm trying to add otel collectors to our spot instance AMIs and configure them so they start automatically on system startup. I'm sure I can find this info somewhere (e.g. https://uptrace.dev/opentelemetry/collector.html#linux) but might be nice to have a section for that in our docs to make it easier to do.