Core Drupal resets settings.php (and the folder containing it) to read-only whenever you visit the System Status page.
This module counters that behavior by forcing the settings file and its containing folder to writable.
This module is not for you
...unless you are a developer who is often fighting against Drupal making your settings.php file read-only. While this is helpful from a security standpoint, it can be obnoxious in the early stages of local development when frequent changes to that file are often necessary.