So how does this work exactly?

It looks like you wrote a script.js file, which calls showdown.js library (converting markdown to html). A uglified version called `md-page` is made pulling both resources

Basically, the script does following

1) wait for page to load

2) add css-styles via javascript

3) shove all the markdown in a variable "markdown", passing it as one giant string

4) Add settings for showdown.js

5) Rewrite entire markdown on page to HTML via showdown.js

6) Append to body and render

I could fork it and add breakpoints / run debugger but this is what I got from looking at source code