Markdown Previewer challenge

Tell us what’s happening:
There is no documentation for the marked.js library given in this challenge.

Please, help with it’s API Docs.
Or, any other markdown API with simple and clean Documentation

Your code so far

Your browser information:

User Agent is: Mozilla/5.0 (Linux; Android 8.0.0; moto e5 plus) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Mobile Safari/537.36.

Challenge: Build a Markdown Previewer

Link to the challenge: