Updates

This feature allows sub-tree directory parsing of `markdown` docs from `/docs` directory.

In few, now you can manage documents as:

```
/docs
|-- index.md
|-- format.md
|-- api
   |-- get.md
   |-- post.md
   |-- delete.md
...
```

Also add some docs on `node-markdocs` internal API with comment blocks.
`[\s\n\r]` is redundant as `\s` [already includes](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/RegExp) `\n` and `\r`