docs: prefer shorter demo

src/picker/README.md

@@ -41,9 +41,7 @@ export default {
     const onChange = (value, index) => {
       Toast(`Value: ${value}, Index: ${index}`);
     };
-    const onCancel = () => {
-      Toast('Cancel');
-    };
+    const onCancel = () => Toast('Cancel');
 
     return {
       columns,

src/picker/README.zh-CN.md

@@ -49,9 +49,7 @@ export default {
     const onChange = (value, index) => {
       Toast(`当前值: ${value}, 当前索引: ${index}`);
     };
-    const onCancel = () => {
-      Toast('取消');
-    };
+    const onCancel = () => Toast('取消');
 
     return {
       columns,

src/picker/demo/index.vue

@@ -183,9 +183,7 @@ export default {
       Toast(t('toastContent', value, index));
     };
 
-    const onCancel = () => {
-      Toast(t('cancel'));
-    };
+    const onCancel = () => Toast(t('cancel'));
 
     const onCancel2 = () => {
       state.showPicker = false;