Add content/en/docs/kubernetes/operator/api.md

[CharlieTLe]

Copying from opentelemetry-operator/docs/api.md so that it can accessible from the website.

Related to: open-telemetry/opentelemetry-operator#3681

[chalin]

Hi. We can't just use a copy of that file, it'll quickly drift from its canonical source. @open-telemetry/operator-approvers should comment as to whether they'd actually like this to appear on the website, and if so, we'll see how we can setup a means of keeping this copy and the operator repo copy in sync.

[swiatekm]

I don't think it's a good idea to host the CRD definitions on opentelemetry.io, if only because they change between versions. We can solve the original issue in the operator repo without involving this one.

[tiffany76]

Closing this PR since the Operator SIG will handle in their repo. Thanks for being proactive, @CharlieTLe!

[chalin]

@CharlieTLe - I've created the following issue so that we can address your very legitimate concern of wanting to be able to view the API docs :)

• Kubernetes operator page refers to API doc that can only be viewed as mostly unusable raw text view #6200