Update redirect-all-different-domain-root.mdx

[cf-scott]

Retaining the example URLs from the original Bulk Redirect instructions, replace Bulk Redirect with an easier-to-use Wildcard Redirect Rule.

Summary

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Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.