dhi: add skip-tlog info (#23274)

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## Description

Added `--skip-tlog` flag info to validate topic.

https://deploy-preview-23274--docsdocker.netlify.app/dhi/how-to/verify/#handle-missing-transparency-log-entries

Vale: Added Rekor to vocab.

## Related issues or tickets

DHI-647

## Reviews

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- [ ] Technical review
- [ ] Editorial review
- [ ] Product review

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

_vale/config/vocabularies/Docker/accept.txt

@@ -159,6 +159,7 @@ Qualcomm
 Quickview
 rebalance
 reimplement
+Rekor
 rollback
 rootful
 runc