WIP

Generate markdown footer links.

Example:

``markdown - [md-footer](https://github.com/sayanarijit/md-footer) -ignoreme`

```

Will convert into

``markdown - [md-footer][1] -ignoreme`

```

Usage:

```bash cat /path/fo/file.md | md-footer

or

md-footer /path/to/file.md ```

It was used to generate footer links for the xplr book.