[IzaakGough]

Fixes #3274.

The README said FUNCTION_DEFAULT_REGION is never read and that an empty BUCKET_REGION keeps the deployed region. Neither is true in an installed project, so users could not predict where the function would deploy.

This documents FUNCTION_DEFAULT_REGION as the fallback when BUCKET_REGION is empty, and adds it to the configuration table.

Based on the CLI's install and migrate templates and the deploys measured in the issue. Not redeployed for this change.

[gemini-code-assist]

Code Review

This pull request updates the README.md for the storage-resize-images kit to document the FUNCTION_DEFAULT_REGION environment variable and clarify its behavior alongside BUCKET_REGION. Feedback suggests correcting the documentation for FUNCTION_DEFAULT_REGION to show it as optional and not prompted, as it is only a fallback and not defined in config.ts.

[gemini-code-assist]

Marking FUNCTION_DEFAULT_REGION as Required: yes and Default: (prompted) is misleading. Since it is not defined as a parameter in config.ts, the Firebase CLI will not prompt for it during a regular deploy if it is missing from .env. Additionally, it is only used as a fallback when BUCKET_REGION is empty, so it is not strictly required for the kit to function.

Suggested change

	| (none) | `FUNCTION_DEFAULT_REGION` | yes | (prompted) | Function region when `BUCKET_REGION` is empty ([details](#bucket_region-decides-where-the-function-runs)) |
	| (none) | <code>FUNCTION_DEFAULT_REGION</code> | no | (empty) | Function region when <code>BUCKET_REGION</code> is empty ([details](#bucket_region-decides-where-the-function-runs)) |