jsonnet: annotate default container for node-exporter DS

[paulfantom]

Description

Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request.
If it fixes a bug or resolves a feature request, be sure to link to that issue.

Specify which container is a default in pod.

This simplifies operations like log retrieval. With this change instead of:

kubectl logs <node-exporter-pod> -c node-exporter

we can do

kubectl logs <node-exporter-pod>

Tested in thaum-xyz/ankhmorpork@92f5aba

Type of change

What type of changes does your code introduce to the kube-prometheus? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Changelog entry

Please put a one-line changelog entry below. Later this will be copied to the changelog file.

Specify default container in node-exporter pod

[ArthurSens]

LGTM, but looks like a comma is missing 😬

[paulfantom]

fixed :)