Minor fix for a constant Javadoc

Author: Snipx

src/main/java/com/itextpdf/html2pdf/css/CssConstants.java

@@ -112,7 +112,7 @@ public class CssConstants extends CommonCssConstants {
     /** The Constant VERTICAL_ALIGN. */
     public static final String VERTICAL_ALIGN = "vertical-align";
 
-    /** The Constant VISIBILITY. */
+    /** The Constant VISIBLE. */
     public static final String VISIBLE = "visible";
 
     /** The Constant MAX_WIDTH. */