bugfix: Add new line after block of definitions

[vvvar]

Problem

When there is a definition followed by any block like this:

[1]: https://www.example.org
[2]: https://www.example.com
## Something

fmt does not adds new line after the last defintion. Also, when in the source fie there's a definition with newline

[2]: https://www.example.com

## Something

it is removed after fmt so it becomes this:

[2]: https://www.example.com
## Something

Solution

Handle when link definition is followed by anything except another definiton and add newline.