docs: batch-import-findings limit

[AndrewCharlesHay]

Description

This doesn't really solve anything but points out issue and proposes work around. If someone has an actual fix I would really appreciate it

Related issues

• Close aws securityhub batch-import-findings Errors with more than 100 findings #2849

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've updated the documentation with the relevant information (if needed).
• I've added tests that prove my fix is effective or that my feature works.
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[knqyf263]

Thanks