trainer: "zero-trust" security / networking for training jobs

[Garvit-77]

Description of Changes

This pr includes documentation for enabling users to implement "Zero-trust" network policy

Related Issues

Closes: trainer #2341
Related: trainer #2341

Checklist

• [Y] You have signed off your commits
• [Y] Ensure you follow best practices from our contributing guide.
• [Y] (for big changes) I will post screenshots of the changes in a PR comment

[google-oss-prow]

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[google-oss-prow]

Hi @Garvit-77. Thanks for your PR.

I'm waiting for a kubeflow member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[github-actions]

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[Arhell]

/ok-to-test