Allow for crate specific maintainers/approvers

[hdost]

We need to see if anyone would like to own and maintain it, otherwise remove it.

is this restricted to the maintainers or do you accept volunteers like me as well? @cijothomas

It is open to all, but there could be some requirements (which we haven't written down here yet). For example, one requirement is that you join the OpenTelemetry organization, and that you can respond to issues reported to the component in a reasonable time etc. It may take a while before we formally write these down, but until then we can continue with this crate.

The general guidelines are here https://github.com/open-telemetry/community/blob/main/CONTRIBUTING.md this applies to the organization.

Our SIGs contribution guidelines are https://github.com/open-telemetry/opentelemetry-rust-contrib/blob/main/CONTRIBUTING.md

However agreed we don't have a subset for these contrib crates. I think if we can have at least a set of approvers for the various contrib crates that would be great

Originally posted by @hdost in #33 (comment)