documentation update for #29

src/xdocs/config_modifier.xml

@@ -95,6 +95,11 @@
           declarations in interface definitions as a matter of style.
         </p>
 
+        <p>
+          Interfaces by definition are abstract so the <code>abstract</code>
+          modifier on the interface is redundant.
+        </p>
+
         <p>
           Variables in interfaces and annotations are automatically
           public, static and final, so these modifiers are redundant as