Tweak inline comment.

Author: garydgregory

src/main/java/org/apache/commons/xml/XPathHardener.java

@@ -97,7 +97,7 @@ private static void setOptionalFeature(final XPathFactory factory, final String
         try {
             factory.setFeature(feature, value);
         } catch (final XPathFactoryConfigurationException e) {
-            // Ignored: the implementation does not recognize this option.
+            // Ignored: the implementation does not recognize this optional feature.
         }
     }