Fixed wrong usage of the ternary operator

`$service->getDescription() !== '' ?: 'No Description'`

Means use the result of `$service->getDescription() !== ''` if it is not a falsey value or use `'No Description'` otherwise.

The result of `$service->getDescription() !== ''` is `1`, so `1` gets printed:

````
$ vendor/bin/bldr task:list
+-------------------+-------------+
| Name              | Description |
+-------------------+-------------+
| exec              | 1           |
| apply             | 1           |
| background        | 1           |
| filesystem:remove | 1           |
| filesystem:mkdir  | 1           |
| filesystem:touch  | 1           |
| filesystem:dump   | 1           |
| notify            | 1           |
| watch             | 1           |
| mysql:user        | 1           |
| sleep             | 1           |
| service           | 1           |
+-------------------+-------------+
````