fix(network): Indent of readme

[Reasonably]

What does this PR do?

• fix yaml indent

Motivation

• https://docs.datadoghq.com/ko/integrations/network/#kubernetes I read the page, and copy & paste to my config. But it seems to invalid

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Changelog entries must be created for modifications to shipped code
• [ ] Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• [ ] If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged