Update README formatting and binary origin docs

Author: raub

README.md

@@ -7,26 +7,23 @@ This is a part of [Node3D](https://github.com/node-3d) project.
 [![Test](https://github.com/node-3d/webaudio/actions/workflows/test.yml/badge.svg)](https://github.com/node-3d/webaudio/actions/workflows/test.yml)
 [![Cpplint](https://github.com/node-3d/webaudio/actions/workflows/cpplint.yml/badge.svg)](https://github.com/node-3d/webaudio/actions/workflows/cpplint.yml)
 
-```console
+```bash
 npm install @node-3d/webaudio
 ```
 
-## Binary Provenance
+## Binary Origin
 
-Release binary archives for this package are published by public GitHub Actions
-workflows.
-When a release asset includes a GitHub Artifact Attestation, you can verify that
-the downloaded archive was published by the visible workflow in this repository:
+Release archives are built by this repository's public GitHub Actions workflows.
 
-```console
+Attestations: https://github.com/node-3d/webaudio/attestations
+
+To verify a downloaded archive:
+
+```bash
 gh release download <tag> -R node-3d/webaudio -p <platform>.gz
 gh attestation verify <platform>.gz -R node-3d/webaudio
 ```
 
-The attestation links the archive to the repository, workflow, commit, and
-release build identity. It does not replace review of the source code, workflow,
-or third-party library contents.
-
 > This addon is ABI-compatible across Node.js versions. **There is no compilation** during `npm install`.