Link to supported schema versions

What does this MR do and why?

Provide more information about supported schema versions in the secure integration docs.

This is a boring solution before we're able to auto-generate this information into the docs based on the source code.

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.