完善后台发布软文提示

jpress-web-admin/src/main/java/io/jpress/admin/controller/_ContentController.java

@@ -405,7 +405,7 @@ public class _ContentController extends JBaseCRUDController<Content> {
 
 		Content dbContent = ContentQuery.me().findBySlug(content.getSlug());
 		if (dbContent != null && content.getId() != null && dbContent.getId().compareTo(content.getId()) != 0) {
-			renderAjaxResultForError();
+			renderAjaxResultForError("标题重复！");
 			return;
 		}