docs: update Docker Hub official image link for mongo (library -> _)

[Navadeep0007]

What changed

Replaced outdated Docker Hub link for the official mongo image:

• https://hub.docker.com/r/library/mongo/... → https://hub.docker.com/_/mongo/...

Why

Official images are served under the /_/ namespace on Docker Hub. Updating these links avoids redirects and potential 404s.

Files changed

• content/manuals/engine/security/trust/_index.md

How tested

• Verified the replacement with git grep.
• Manually opened the updated link in a browser to confirm it points to the mongo image tags page.

Closes: #23622

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[Navadeep0007]

Hi @dvdksn and @docker/docs-maintainers 👋
This is a small docs-only fix that updates an outdated Docker Hub link for the official mongo image (library/mongo → _/mongo).

✅ All checks and deploy previews are passing.
Would appreciate a quick review and approval whenever convenient. Thank you for maintaining such a great project!

[Navadeep0007]

Hi @dvdksn and @docker/docs-maintainers 👋
This is a small docs-only fix that updates an outdated Docker Hub link for the official mongo image (library/mongo → _/mongo).

✅ All checks and deploy previews are passing.
Would appreciate a quick review and approval whenever convenient. Thank you for maintaining such a great project!

[dvdksn]

Thanks!