Feature Request: Markdown Handling

[lyqht]

Hi there, thanks for the great library to use the DeepL API!

I made a github action for using deepl-node to translate text documents, however there's quite a lot of limitations in trying to parse markdown elements.

You can refer to some limitations that's mentioned in this demo or this PR.

The formatting errors that were raised in both examples may be due to the use of markdown checkboxes, bolded text etc, since most other HTML elements were able to be translated accurately, and only break on certain languages.