Config: add newline between last property and first child category of categories.

Changes
```
parent {
    # This is the last property of the parent category.
    # It becomes easy to miss this as it currently is.
    B:lastProperty=false
    ####################
    # child
    ####################

    child {
        ...
```
to
```
parent {
    # This is the last property of the parent category.
    # It becomes easy to miss this as it currently is.
    B:lastProperty=false

    ####################
    # child
    ####################

    child {
        ...
```