docs: restore original SLSA framework text in README.md

Author: keelerm84

README.md

@@ -63,10 +63,10 @@ Contributing
 
 We encourage pull requests and other contributions from the community. Check out our [contributing guidelines](CONTRIBUTING.md) for instructions on how to contribute to this library.
 
-Verifying library build provenance with GitHub artifact attestations
+Verifying library build provenance with the SLSA framework
 ------------
 
-LaunchDarkly uses [GitHub artifact attestations](https://docs.github.com/en/actions/security-for-github-actions/using-artifact-attestations/using-artifact-attestations-to-establish-provenance-for-builds) to help developers make their supply chain more secure by ensuring the authenticity and build integrity of our published library packages. To learn more, see the [provenance guide](PROVENANCE.md).
+LaunchDarkly uses the [SLSA framework](https://slsa.dev/spec/v1.0/about) (Supply-chain Levels for Software Artifacts) to help developers make their supply chain more secure by ensuring the authenticity and build integrity of our published library packages. To learn more, see the [provenance guide](PROVENANCE.md).
 
 About LaunchDarkly
 -----------