Undesirable escaping of trailing backslashes

Unfortunately, `documentation` escapes trailing backslashes that are meant for intentional line breaks.

* What version of documentation.js are you using?:
* version 9.3.1

* How are you running documentation.js (on the CLI, Node.js API, Grunt, other?):
* CLI: `npx documentation readme --section API index.js`

> `README.md` before
```md
Line 1\
Line 2

## API
```

> `README.md` after
```md
Line 1\\
Line 2

## API
[..]
```