Request to add Markdown support

[devils2ndself]

Hello! I would like to add basic Markdown support to this project. This includes:

• Support for reading .md files
• Markdown Heading 1 feature
• Markdown Heading 2 feature

Please, let me know if you approve of these changes.

For reference, here are the examples of what I would like to work on:

Heading 1

Heading 2

[rudychung]

In the HTML output, the heading line is on the same line the previous line. Could you update the code so that there is a line break between the heading line and the previous line?

Here is an example of what I am talking about: