Support content-type text/markdown

[gitblit]

I have checked the following:

• I've searched existing issues and found nothing related to my issue.

Describe the feature you want to add

I have some endpoints that can return data in multiple formats. One of those formats is PDF (already supported 🎉) and another is Markdown. It would be great to be able to render the Markdown content properly. It appears Bruno may already support markdown internally for endpoint documentation, maybe that can be leveraged to support api responses.

Mockups or Images of the feature

I don't have a mockup to share.