Documentation does not describe how to use Markdown feature

Cursive does have a `markdown` feature flag, but it is not documented how to display Markdown e.g. in a TextView.

There is also no example code.

This is what I have come up with so far:

``` rust
use cursive::utils::markup::markdown::parse;

let content = parse(include_str!("LICENSE.md"));
// `content` is a `SpannedString` with styles, I can see that when I dump it
let text_view = TextView::new(content)
.scrollable()
[...]
```

The output is not styled, it is rather garbled, as it strips newlines, see screenshot: The '## Overview' heading should really start on a new line.