   `import Config` will import the functions `config/2`, `config/3`
   and `import_config/1` to help you manage your configuration.
 
-  Once Mix starts, it will automatically evaluate the configuration
-  file and persist it into `:some_app`'s application environment, which
-  can be accessed in as follows:
+  `config/2` and `config/3` are used to define key-value configuration
+  for a given application. Once Mix starts, it will automatically
+  evaluate the configuration file and persist the configuration above
+  into `:some_app`'s application environment, which can be accessed in
+  as follows:
 
       "value1" = Application.fetch_env!(:some_app, :key1)
 
-  See `Config.Reader` for evaluating and reading configuration
-  files.
+  Finally, the line `import_config "#{Mix.env()}.exs"` will import other
+  config files, based on the current Mix environment, such as
+  `config/dev.exs` and `config/test.exs`.
+
+  `Config` also provides a low-level API for evaluating and reading
+  configuration, under the `Config.Reader` module.
 
   **Important:** if you are writing a library to be used by other developers,
   it is generally recommended to avoid the application environment, as the


  ## Example

  This module is most commonly used to define application
  configuration, typically in `config/config.exs`:

      import Config


        import_config config
      end

  ## config/releases.exs

  If you are using releases, see `mix release`, there another configuration
  file called `config/releases.exs`. While `config/config.exs` and friends
  mentioned in the previous section are executed whenever you run a Mix
  command, including when you assemble a release, `config/releases.exs` is
  execute every time your production system boots. Since Mix is not available
  in a production system, `config/releases.exs` must not use any of the
  functions from Mix.
  """

  @config_key {__MODULE__, :config}
