Navigation Treeview Example: Correct typo: change 'an' to 'and' in ac…

…cessibility features (pull #2776)

Incorrect text:

>Because transparent borders are visible on some systems with operating system high contrast settings enabled, transparency cannot be used to create a visual difference between the element that is focused an other elements.

Corrected text:

>Because transparent borders are visible on some systems with operating system high contrast settings enabled, transparency cannot be used to create a visual difference between the element that is focused and other elements.

content/patterns/treeview/examples/treeview-navigation.html

@@ -354,7 +354,7 @@ <h3>Visual design and high contrast features</h3>
             To support operating system high contrast settings:
             <ul>
               <li>
-                Because transparent borders are visible on some systems with operating system high contrast settings enabled, transparency cannot be used to create a visual difference between the element that is focused an other elements.
+                Because transparent borders are visible on some systems with operating system high contrast settings enabled, transparency cannot be used to create a visual difference between the element that is focused and other elements.
                 Instead of using transparency, the focused element has a thicker border and less padding.
                 When an element receives focus, its border changes from 1 to 3 pixels and padding is reduced by 2 pixels.
                 When an element loses focus, its border changes from 3 pixels to 1 and padding is increased by 2 pixels.