title: React Native - Stack Navigator Check from which screen has the new panel been opened
body: <p>I am using <a href="https://reactnavigation.org/docs/stack-navigator.html" rel="nofollow noreferrer">Stack Navigator</a> for navigating between screens. I have a Info screen which can be accessed from two other different screens in my app. Depending from which screen I have tried to access my Info panel, different text should be displayed on it. How can I check which was the screen before the current one(the info screen)? </p>
  
  <p>I tried playing with <code>this.props.navigation.state.routeName</code>. However, it would only return the name of the current panel, not the one before. Is there any way I can check the previous one or at least get its' name?</p>