Sometimes, including default configuration objects defined by other modules is not enough, and you may want to define your own configuration. As with many other parts of the Configuration Management in Drupal 8, this is not very complicated.
Configuration files for configuration objects defined by a module reside in the config/install subdirectory of this module. In our example, this is /modules/custom/cm_example/config/install.
Tip
We put our example module in a directory named custom inside the modules directory to separate contributed modules downloaded from https://drupal.org from custom modules. This is a well-known best practice when creating sites to keep your modules organized.
In Chapter 3, Drupal 8's take on Configuration Management, we mentioned the naming conventions of configuration files. As said before, simple module settings should go into a file named <module name>.settings.yml; thus, in our case...