Change sortId to currentField in sort directive

In documentatin was type, where it said to use sortId to select element from which items should be filtered, however currentField is the option which shuld be used.
No changes in code, just in usage documentation

Author: karelhala

dist/angular-patternfly.js

@@ -775,10 +775,12 @@ angular.module('patternfly.card').directive('pfCard', function () {
             var chart;
             //generate c3 chart data
             var chartData = scope.config;
-            chartData.bindto = '#' + attrs.id;
-            chart = c3.generate(chartData);
-            if (scope.getChartCallback) {
-              scope.getChartCallback(chart);
+            if (chartData) {
+              chartData.bindto = '#' + attrs.id;
+              chart = c3.generate(chartData);
+              if (scope.getChartCallback) {
+                scope.getChartCallback(chart);
+              }
             }
           });
         }, true);
@@ -4008,7 +4010,7 @@ angular.module('patternfly.select', []).directive('pfSelect', ["$timeout", funct
  * <li>.title       - (String) The title to display for the sort field
  * <li>.sortType    - (String) The sort type, 'alpha' or 'numeric'
  * </ul>
- * <li>.sortId   - (Object) Id of the current sort field
+ * <li>.currentField   - (Object) Currently selected field
  * <li>.isAscending - (boolean) Current sort direction is ascending. True for ascending, False for descending
  * <li>.onSortChange - ( function(sortId, sortDirection ) Function to call when the current sort params change
  * </ul>