Create upgrade docs to keep track of changes between backwards incompatible versions

app/Subscribers/CommandSubscriber.php

@@ -15,7 +15,6 @@ use CachetHQ\Cachet\Bus\Events\System\SystemWasInstalledEvent;
 use CachetHQ\Cachet\Bus\Events\System\SystemWasResetEvent;
 use CachetHQ\Cachet\Bus\Events\System\SystemWasUpdatedEvent;
 use CachetHQ\Cachet\Settings\Cache;
-use Exception;
 use Illuminate\Console\Command;
 use Illuminate\Contracts\Config\Repository;
 use Illuminate\Contracts\Events\Dispatcher;
@@ -128,7 +127,7 @@ class CommandSubscriber
     }
 
     /**
-     * Handle the main bulk of the command, clear the settings
+     * Handle the main bulk of the command, clear the settings.
      *
      * @param \Illuminate\Console\Command $command
      *

docs/upgrade/UPGRADE-2.4.md

@@ -0,0 +1,10 @@
+# Upgrading cachet 2.3 to 2.4
+
+# PHP 7
+Cachet 2.4 is build using the Laravel 5.6 which requires at least PHP 7.1.3 or higher.
+
+# Backups
+In previous versions Cachet would ship with `backup-manager/laravel` to create database backups at certain points when 
+running the software. This is no longer provided by default in 2.4. You are free to implement your custom backup 
+solution when running cachet on your environments. If you do prefer a backup solution close to the pre 2.4 Cachet version: 
+Spatie has created [a backup manager](https://github.com/spatie/laravel-backup) that comes close to the original implementation.