Allow exception rendering to auto-detect based on environment.

Add additional documentation for new options in 4.4

Author: markstory

config/app.php

@@ -166,8 +166,9 @@
      * - `log` - boolean - Whether or not you want exceptions logged.
      * - `exceptionRenderer` - string - The class responsible for rendering
      *   uncaught exceptions. If you choose a custom class you should place
-     *   the file for that class in src/Error. This class needs to implement a
-     *   render method.
+     *   the file for that class in src/Error. This class needs to implement a `render()` method.
+     *   `errorRenderer` - string - The class responsible for rendering PHP errors. This class needs
+     *   to implement the `Cake\Error\ErrorRendererInterface`.
      * - `skipLog` - array - List of exceptions to skip for logging. Exceptions that
      *   extend one of the listed exceptions will also be skipped for logging.
      *   E.g.:
@@ -181,7 +182,6 @@
      */
     'Error' => [
         'errorLevel' => E_ALL,
-        'exceptionRenderer' => ExceptionRenderer::class,
         'skipLog' => [],
         'log' => true,
         'trace' => true,