System Spec feature: include System Tests text

Author: olleolleolle

features/system_specs/system_specs.feature

@@ -2,11 +2,18 @@ Feature: System spec
 
     System specs are RSpec's wrapper around Rails' own
     [system tests](http://guides.rubyonrails.org/testing.html#system-testing).
-    We encourage you to familiarize yourself with their documentation.
-
-    RSpec **does not** use your `ApplicationSystemTestCase` helper. Instead it uses
-    the default `driven_by(:selenium)` from Rails. If you want to override this
-    behaviour you can call `driven_by` manually in a test.
+    
+    System tests allow you to test user interactions with your application,
+    running tests in either a real or a headless browser. System tests use
+    Capybara under the hood.
+
+    By default, system tests are run with the Selenium driver, using the Chrome
+    browser, and a screen size of 1400x1400. The next section explains how to
+    change the default settings.
+
+    RSpec **does not** use your `ApplicationSystemTestCase` helper. Instead it
+    uses the default `driven_by(:selenium)` from Rails. If you want to override
+    this behaviour you can call `driven_by` manually in a test.
 
 
     @system_test