Create a ref doc for pod security policy

[pweil-]

@devin-donnelly 1.4 version as requested in #1150 (comment). Updates have been made in both PRs. Thanks!

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This change is

[devin-donnelly]

Docs LGTM. This does look like it needs a tech review.

[erictune]

s/SCC/PSP/

[devin-donnelly]

Should this be fixed before merge? I'll mark it as Tech Review: Open Issues.

[pweil-]

Yes. This is updated now..

[devin-donnelly]

Thanks, merging now.

[nikhiljindal]

This PR seems to have broken deploy/netlify on release-1.4 branch.

It is failing on all PRs with the following error (Ref #1222 (comment)):

3:27:46 PM: Liquid Exception: Could not locate the included file 'sj.yaml' in any of ["/opt/build/repo/docs/user-guide/pod-security-policy"]. Ensure it exists in one of those directories and, if it is a symlink, does not point outside your site source. in docs/user-guide/pod-security-policy/index.md
3:27:46 PM: jekyll 3.2.1 | Error: Could not locate the included file 'sj.yaml' in any of ["/opt/build/repo/docs/user-guide/pod-security-policy"]. Ensure it exists in one of those directories and, if it is a symlink, does not point outside your site source.
3:27:46 PM: make: *** [build-preview] Error 1

docs/user-guide/pod-security-policy/index.md added in this PR is referring to sj.yaml file that does not exist.

[pweil-]

looking