dhi: add build transparency (#24136)

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## Description

Add transparency benefit to the build conceptual topic.


https://deploy-preview-24136--docsdocker.netlify.app/dhi/explore/build-process/

## Related issues or tickets

ENGDOCS-3191

## Reviews

<!-- Notes for reviewers here -->
<!-- List applicable reviews (optionally @tag reviewers) -->

- [ ] Editorial review
- [ ] Product review

---------

Signed-off-by: Craig Osterhout <craig.osterhout@docker.com>

content/manuals/dhi/explore/build-process.md

@@ -18,6 +18,25 @@ both base and customized images is backed by SLA commitments, including a 7-day
 SLA for critical and high severity vulnerabilities. Only DHI Enterprise includes
 SLAs. DHI Free offers a secure baseline but no guaranteed remediation timelines.
 
+## Build transparency
+
+Docker Hardened Images provide transparency into how images are built through
+publicly available definitions and verifiable attestations.
+
+### Image definitions
+
+All image definitions are publicly available in the [catalog
+repository](https://github.com/docker-hardened-images/catalog).
+
+Each image definition is a declarative YAML specification that includes metadata,
+contents, build pipeline steps, security configurations, and runtime settings.
+
+### SLSA attestations
+
+Every Docker Hardened Image includes a SLSA Build Level 3 attestation that
+provides verifiable build provenance. For details on SLSA attestations and how to
+verify them, see [SLSA](../core-concepts/slsa.md).
+
 ## Build triggers
 
 Builds start automatically. You don't trigger them manually. The system monitors