change text of MarkText example to match styling

Author: michaelficarra

css-color-4/Overview.bs

@@ -1755,7 +1755,7 @@ System Colors</h3>
 		<p>ButtonFace with GrayText <span style="background-color:ButtonFace; color:GrayText">GrayText</span></p>
 		<p>Field with FieldText <span style="background-color:Field; color:FieldText">FieldText</span></p>
 		<p>Field with GrayText <span style="background-color:Field; color:GrayText">GrayText</span></p>
-		<p>Mark with MarkText <span style="background-color:Mark; color:MarkText">FieldText</span></p>
+		<p>Mark with MarkText <span style="background-color:Mark; color:MarkText">MarkText</span></p>
 		<p>Mark with GrayText <span style="background-color:Mark; color:GrayText">GrayText</span></p>
 		<p>Highlight with HighlightText <span style="background-color:Highlight; color:HighlightText">HighlightText</span></p>
 		<p>Highlight with GrayText <span style="background-color:Highlight; color:GrayText">GrayText</span></p>