docs: update appType docs

[benmccann]

Description

The same middlewares are included for both SPA and MPA mode, but you wouldn't necessarily conclude that from the docs currently. The only different is that in SPA mode the fallback middleware is configured with the spaFallback option

Additional context

Followup to #10985

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
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• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Thanks!