What problem does this feature solve?
Bicep is the a 'new' DSL created by Microsoft. It enables us developers to create better ARM templates.
More information can be found over here: https://docs.microsoft.com/en-us/azure/azure-resource-manager/bicep/overview

Where ARM Templates are just a different flavor of JSON, Bicep has a different syntax.

At the moment, specifying the bicep language will result in having a non-highlighted code block.

What feature do you propose?
Implement the Bicep language for syntax highlighting.

I haven't looked at the code of this project yet, but it sounds like a good first issue for someone to pick up.