Introduction to chain-config.yml
This file is mainly for people that are trying to contribute to the Casper theme. This is an easy was to export the configuration that Casper carries by default. If you have made any new changes to the configuration, using DrupalConsole you can re-export all the configuration again without need of any extra steps.
How to run chain config ?
From the root directory of you Drupal website you can run something similar too.