dhi: add keywords to mirroring (#23556)

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## Description

Added more keywords based on internal feedback of being unable to find
the topic via keyword search with certain terms: `internal registry` and
third-party registry names

## Related issues or tickets

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## Reviews

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- [ ] Editorial review

Signed-off-by: Craig Osterhout <[email protected]>

Author: craig-osterhout

content/manuals/dhi/how-to/mirror.md

@@ -3,7 +3,7 @@ title: Mirror a Docker Hardened Image repository
 linktitle: Mirror an image
 description: Learn how to mirror an image into your organization's namespace and optionally push it to another private registry.
 weight: 20
-keywords: mirror docker image, private container registry, docker hub automation, webhook image sync, secure image distribution
+keywords: mirror docker image, private container registry, docker hub automation, webhook image sync, secure image distribution, internal registry, jfrog artifactory, harbor registry, amazon ecr, google artifact registry, github container registry
 ---
 
 {{< summary-bar feature_name="Docker Hardened Images" >}}