Provide styling for Markdown content in sections

[dbellomo]

full markdown processing don't work on sections. e.g, can't processing "#" and ">" tags

[ttntm]

I don't see anything wrong with Markdown processing:

All tags input into sections/about.md render as respective HTML elements.

In conclusion: this is a styling issue rathern than a functional limitation.

What's left to do:

1. Add a custom class (i.e. md-content) to line 6 in ./src/includes/section.about.njk
2. Write some CSS targeting the children of this class and put it at the bottom of ./src/inludes/css/custom.css

I'll see when I can get around to doing that, pull requests would be much appreciated though.