Add strawperson (stage 0) Kubernetes RFC

[ferozsalam]

I have written a strawperson RFC stub to begin the process of moving the existing Kubernetes use-case into a full ECS schema of its own. More details are in the commit diff, please let me know if there's anything more I can clarify.

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• Have you signed the contributor license agreement? Yes
• Have you followed the contributor guidelines? Yes
• For proposing substantial changes or additions to the schema, have you reviewed the RFC process? Yes
• If submitting code/script changes, have you verified all tests pass locally using make test? N/A
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• Is your pull request against master? Yes
• Have you added an entry to the CHANGELOG.next.md? N/A

[ebeahan]

Thanks for writing this and submitting it, @ferozsalam!

Adding fields to better support container orchestration solutions has been discussed, but this proposal is a great step towards formalizing the conversation.

[ferozsalam]

@ebeahan Thanks for your review! I have addressed all your comments, let me know if this looks OK now.

Edit: made some more tweaks so that the RFC summary is more generic and less k8s-specific.

[ebeahan]

Thanks for the updates! LGTM 👍

I'll assign the RFC a number, set the date in the proposal, and merge.

[ebeahan]

Once again, thanks, @ferozsalam, for submitting this PR.

We'll work on identifying a sponsor for this RFC within Elastic.

If you're willing to keep working on this, you're welcome to open the stage one pull request. If not, your feedback is welcomed on any following stage PRs! 😃

In stage one, we'll want to address the following:

• Propose an initial set of field definitions for orchestrator.*.
• Describe further at a high-level how these fields will be used in practice
• Include real-world example documents.
• Identify any potential concerns, implementation challenges, or complexity.
• Officially identify the sponsor (that one's on Elastic's end 😄 )

[ferozsalam]

Hey @ebeahan I definitely intend to see this through, but it's been a busy week! I expect to have a draft ready before 7pm UTC tomorrow.