Add description to fix composer show --tree

While running:

```
composer show --tree
```

It fails if this package is installed since the `description` key is empty. See composer source code where `strtok` fails since description is null instead of string type: https://github.com/composer/composer/blob/main/src/Composer/Command/ShowCommand.php#L1127

I added a very simple description, nothing too fancy!

Author: bradleybernard

composer.json

@@ -1,6 +1,6 @@
 {
     "name": "hammerstone/fast-paginate",
-    "description": "",
+    "description": "Fast paginate for Laravel",
     "type": "library",
     "license": "MIT",
     "authors": [