Update maintenance status in readme

[mattjw79]

Description

Fixes # (issue)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Checklist: (Feel free to delete this section upon completion)

• I have included a changeset if this change will require a version change to one of the packages.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have run all builds, tests, and linting and all checks pass
• I have added tests that prove my fix is effective or that my feature works
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules