Added more comments

src/app/core/submission/workflowitem-data.service.ts

@@ -14,6 +14,9 @@ import { NotificationsService } from '../../shared/notifications/notifications.s
 import { ObjectCacheService } from '../cache/object-cache.service';
 import { DSOChangeAnalyzer } from '../data/dso-change-analyzer.service';
 
+/**
+ * A service that provides methods to make REST requests with workflowitems endpoint.
+ */
 @Injectable()
 export class WorkflowitemDataService extends DataService<Workflowitem> {
   protected linkPath = 'workflowitems';