fix readme description syntax error causing release action to fail

[danabens]

Issue #, if available: no issue

Description of changes: release task is currently failing due to a syntax error in the README.rst see https://github.com/aws/sagemaker-experiments/actions/runs/4994718175/jobs/8946259829

Testing done: test release

Merge Checklist

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• [x] I have read the CONTRIBUTING doc
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• [x] I have updated any necessary documentation, including READMEs and API docs (if appropriate)

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