fix: resolve MDX JSX parse error in configure-external-storage-access

[Oreoxmt]

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[LGTM Timeline notifier]

Timeline:

• 2026-04-07 03:14:37.916798993 +0000 UTC m=+839683.122159050: ☑️ agreed by hfxsd.

[Oreoxmt]

/approve

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[gemini-code-assist]

Code Review

This pull request reorganizes the documentation for configuring external storage access by moving introductory sentences for Amazon S3 and Azure Blob Storage exports inside the tags. This change ensures that the instructions are correctly displayed based on the user's service plan (starter, essential, or premium). Additionally, minor formatting improvements were made to the text. I have no feedback to provide.