Documentation: SURREAL_FILE_ALLOWLIST should be changed to SURREAL_BUCKET_FOLDER_ALLOWLIST

### Description

just like this document says 
https://surrealdb.com/docs/surrealdb/querying/surrealism/tutorial

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct