docs: update PROVENANCE.md and README.md for GitHub artifact attestations

Author: keelerm84

PROVENANCE.md

@@ -1,10 +1,10 @@
-## Verifying SDK build provenance with the SLSA framework
+## Verifying SDK build provenance with GitHub artifact attestations
 
-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 SDK packages.
+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 SDK packages.
 
-As part of [SLSA requirements for level 3 compliance](https://slsa.dev/spec/v1.0/requirements), LaunchDarkly publishes provenance about our SDK package builds using [GitHub's generic SLSA3 provenance generator](https://github.com/slsa-framework/slsa-github-generator/blob/main/internal/builders/generic/README.md#generation-of-slsa3-provenance-for-arbitrary-projects) for distribution alongside our packages. These attestations are available for download from the GitHub release page for the release version under Assets > `multiple.intoto.jsonl`.
+LaunchDarkly publishes provenance about our SDK package builds using [GitHub's `actions/attest` action](https://github.com/actions/attest). These attestations are stored in GitHub's attestation API and can be verified using the [GitHub CLI](https://cli.github.com/).
 
-To verify SLSA provenance attestations, we recommend using [slsa-verifier](https://github.com/slsa-framework/slsa-verifier). Example usage for verifying SDK packages is included below:
+To verify build provenance attestations, we recommend using the [GitHub CLI `attestation verify` command](https://cli.github.com/manual/gh_attestation_verify). Example usage for verifying SDK packages is included below:
 
 <!-- x-release-please-start-version -->
 ```
@@ -13,32 +13,24 @@ SDK_VERSION=9.15.0
 ```
 <!-- x-release-please-end -->
 
-
 ```
-# Download package from PyPi
+# Download package from PyPI
 $ pip download --only-binary=:all: launchdarkly-server-sdk==${SDK_VERSION}
 
-# Download provenance from Github release into same directory
-$ curl --location -O \
-  https://github.com/launchdarkly/python-server-sdk/releases/download/${SDK_VERSION}/multiple.intoto.jsonl
-
-# Run slsa-verifier to verify provenance against package artifacts 
-$ slsa-verifier verify-artifact \
---provenance-path multiple.intoto.jsonl \
---source-uri github.com/launchdarkly/python-server-sdk \
-launchdarkly_server_sdk-${SDK_VERSION}-py3-none-any.whl
+# Verify provenance using the GitHub CLI
+$ gh attestation verify launchdarkly_server_sdk-${SDK_VERSION}-py3-none-any.whl -R launchdarkly/python-server-sdk
 ```
 
 Below is a sample of expected output.
 
 ```
-Verified signature against tlog entry index 76390194 at URL: https://rekor.sigstore.dev/api/v1/log/entries/24296fb24b8ad77ac42700bfad5eb5597ea8bda92acb470aade248c01ccfc44047c0cd5b4433021a
-Verified build using builder "https://github.com/slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@refs/tags/v1.7.0" at commit c7b42a2e7486904978d77cf05a07280e7e1bbec2
-Verifying artifact launchdarkly_server_sdk-9.2.2-py3-none-any.whl: PASSED
+Loaded digest sha256:... for file://launchdarkly_server_sdk-9.15.0-py3-none-any.whl
+Loaded 1 attestation from GitHub API
+✓ Verification succeeded!
 
-PASSED: Verified SLSA provenance
+launchdarkly_server_sdk-9.15.0-py3-none-any.whl was attested by a trusted GitHub Actions workflow
 ```
 
-Alternatively, to verify the provenance manually, the SLSA framework specifies [recommendations for verifying build artifacts](https://slsa.dev/spec/v1.0/verifying-artifacts) in their documentation.
+For more information, see [GitHub's documentation on verifying artifact attestations](https://docs.github.com/en/actions/security-for-github-actions/using-artifact-attestations/using-artifact-attestations-to-establish-provenance-for-builds#verifying-artifact-attestations-with-the-github-cli).
 
-**Note:** These instructions do not apply when building our SDKs from source. 
+**Note:** These instructions do not apply when building our SDKs from source.  

README.md

@@ -34,9 +34,9 @@ We run integration tests for all our SDKs using a centralized test harness. This
 
 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 SDK.
 
-## Verifying SDK build provenance with the SLSA framework
+## Verifying SDK build provenance with GitHub artifact attestations
 
-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 SDK packages. To learn more, see the [provenance guide](PROVENANCE.md). 
+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 SDK packages. To learn more, see the [provenance guide](PROVENANCE.md).
 
 ## About LaunchDarkly