 
   The given `opts` are merged into the existing configuration
   for the given `app`. Conflicting keys are overridden by the
-  ones specified in `opts`. For example, the declaration below:
-
-      config :lager,
-        log_level: :warn,
-        mode: :truncate
-
-      config :lager,
-        log_level: :info,
-        threshold: 1024
-
-  Will have a final configuration of:
-
-      [log_level: :info, mode: :truncate, threshold: 1024]
-
-  This final configuration can be retrieved at run or compile time:
-
-      Application.get_all_env(:lager)
+  ones specified in `opts`. For example, the application
+  configuration below
+
+      config :logger,
+        level: :warn,
+        backends: [:console]
+
+      config :logger,
+        level: :info,
+        truncate: 1024
+
+  will have a final configuration for `:logger` of:
+
+      [level: :info, backends: [:console], truncate: 1024]
 
   """
   def config(app, opts) when is_atom(app) and is_list(opts) do


      use Mix.Config

      config :some_app,
        key1: "value1",
        key2: "value2"



  The most common use of `Mix.Config` is to define application
  configuration so that `Application.get_env/3` and other `Application`
  functions can be used to retrieve or further change them.

  Application config files are typically placed in the `config/`
  directory of your Mix projects. For example, the following config

      # config/config.exs
      config :my_app, :key, "value"

  will be automatically loaded by Mix and persisted into the
  `:my_app`'s application environment, which can be accessed in
  its source code as follows:

      "value" = Application.fetch_env!(:my_app, :key1)

