Fix link from an event to a property (#2584)

Author: pkulikov

xml/System.Windows/UIElement.xml

@@ -3329,7 +3329,7 @@ Image with an Elliptical Clip Region
         <ReturnType>System.Windows.DependencyPropertyChangedEventHandler</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>Occurs when the value of the <see cref="E:System.Windows.UIElement.IsKeyboardFocusWithinChanged" /> property changes on this element.</summary>
+        <summary>Occurs when the value of the <see cref="P:System.Windows.UIElement.IsKeyboardFocusWithin" /> property changes on this element.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[