docs(update-certificate-store/README.md): update module/script name

[vdice]

Description

Updates the update-certificate-store module/script name in the module README

Documentation

N/A

TODOs

Please ensure all of these TODOs are completed before asking for a review.

• Ensure the branch is named correctly with the issue number. e.g: feature/new-vpc-endpoints-955 or bug/missing-count-param-434.
• Update the docs.
• Keep the changes backward compatible where possible.
• Run the pre-commit checks successfully.
• Run the relevant tests successfully.
• Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.

Related Issues

N/A

[anouarchattouna]

LGTM

[hashicorp-cla]

All committers have signed the CLA.