Clarify tabs better.

docs/Quick Start/Navigating_in_StoryCAD.md

@@ -10,7 +10,11 @@ has_toc: false
 
 Your outline is a tree of story elements, which are displayed in the Navigation Pane. Here's how to move around in this visual tree, and within a story element, and how to edit properties on a story element.
 
-Adding and removing story elements can be done either from the menu bar's Add button or via a flyout panel from the Navigation Pane.
+You can add and remove story elements either using the menu bar's Add button or via a fly-out panel from the Navigation Pane, as described below.
+
+A story element's Content Pane displays the properties of that story element. We organized the related properties into tabs as described below.
+
+