Document Policy Catalog in getting started doc

[tcnghia]

Is your feature request related to a problem? Please describe. We added a new Policy Catalog UI (https://console.enforce.dev/policies/catalog), which would improves the getting started experience.

We need to update the getting started guide to mention this awesome feature!

Describe the solution you'd like Getting started guides point to https://console.enforce.dev/policies/catalog

Describe alternatives you've considered N/A

Additional context https://github.com/chainguard-dev/console-ui/issues/518

[tcnghia]

Guide is here https://edu.chainguard.dev/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/chainguard-policies-ui/

[tcnghia]

Source code is here https://github.com/chainguard-dev/edu/blob/main/content/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/chainguard-policies-ui/index.md

[tcnghia]

cc @amdawson