Include Local Settings Files in settings.php

Usually while working on a Drupal site in your dev envirement (be it local or remote) you want to inject some settings into the site, for example to disable the cache, set your maillog or mailchimp settings, etc.. Obviously you can add those to the actual settings.php file, or you can have an already made local settings file in a set location (for example $HOME/.drush/default.settings.local.php) that you can just symlink in the site directory and add this snippet to the site settings.php.