title: Serenity session variable usage
body: <p>Hi team am new to serenity. Let's say am storing this data as follows</p>
  
  <pre><code>Serenity.setSessionVariable("User Name").to("userKey");
  </code></pre>
  
  <p>Now in a scenario if I call this key like this <code>Serenity.sessionVariableCalled("userKey")</code> from a different step definition in a different class will I get the value saved?.</p>