For fields that contain markdown, you should support cross-links to other entities.

Markdown supports links to entity ids, in the form documented here:

You could extend this to allow links to be generated to other entities in the catalog. For example:

When Port rendered this markdown, it would translate the element to an internal URL, for example:

https://app.getport.io/anyBlueprintEntity?identifier= anyElement

In this way author can write docs that cross-reference other entities without having hard coded URLs.