Onboard to MAR (formerly MCR) discovery portal

There is now a frontend for browsing content in the Microsoft Artifact Registry: https://mcr.microsoft.com/

It requires manual onboarding.

Start with the Microsoft Artifact Registry discovery portal at https://mcr.microsoft.com/ and determine what manual onboarding for Bicep entails. No repository file, test, or implementation entry point is named in the issue; completion would be successful onboarding, but the required scope and acceptance criteria need clarification first.

Written by the indexing model from the issue text.