Add documentation on updating SRE configurations

[craddm]

✅ Checklist

• You have given your pull request a meaningful title (e.g. Enable foobar integration rather than 515 foobar).
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🚦 Depends on

⤴️ Summary

Adds documentation for the procedure for updating SRE configurations. This includes a direct warning that changes to the admin IP addresses must initially be made from the original IP address.

🌂 Related issues

Closes #2212

🔬 Tests

Documentation only

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[JimMadge]

I've changed the target to develop. I don't think we should make hotfixes from docs-only changes.

[JimMadge]

Good additions.

I think there are some changes around the framing of how this works I'd like to make.