[Docs][Connector-V2][S3File] Fix connector s3file option name (access_secret -> secret_key)

[loupipalien]

Purpose of this pull request

Fix connector s3file option name (access_secret -> secret_key), name is secret_key in the code, but access_secret in the docs

Does this PR introduce any user-facing change?

No

How was this patch tested?

Not need tests for docs

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config

[Carl-Zhou-CN]

+1,Thank you for your contribution @loupipalien