Docs: Update latest artifacts version for expires_in note

What does this MR do?

During our #everyonecancontribute Kaeffchen (German coffee chat) the question came up why the latest artifacts in are not kept. As in the docs note for expire_in mentioned this being in 13.0. We've then analyzed the issue together and found the missed label.

This MR is to help update the docs following the issue being fully resolved in 13.1

cc @thaoyeager

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team