docs: change slot to # (#5858)

* docs(SwipeCell): change "slot" to "v-slot"

* docs(SwipeCell): change `v-slot` to`#`

* docs(cell): change `slot` to `#`

* docs(checkbox): change `slot` to `v-slot`

* docs(field): change `slot` to `v-slot`

* docs(checkbox): remove wrong comment

* docs(radio): change `slot` to `#`

* docs(search): change `slot` to `#`

* docs(slider): change `slot` to `#`

* docs(switch): change `slot` to `#`

* docs(PullRefresh): change `slot` to `#`

* docs(collapse): change `slot` to `#`

* docs(panel): change `slot` to `#`

* docs(swipe): change `slot` to `#`

* docs(navbar): change `slot` to `#`

* docs(tab): change `slot` to `#`

* docs(tabber): change `slot` to `#`

* docs(TreeSelect): change `slot` to `#`

* docs(card): change `slot` to `#`

* docs(submitBar): change `slot` to `#`

* docs(sku): change `slot` to `#` unsure

* docs(cell): delete waste blank line

* docs(panel): fix indentation

* docs(PullRefresh): change "count" to "Refresh Count"

* docs(radio): delete waste blank line

* docs(search): move props above the event

* docs(submitBar): delete waste `<span>`

* docs(swipCell): delete waste blank line

* docs(tabbar): merge `<img>` into one line

src/card/README.md

@@ -49,14 +49,14 @@ Use slot to custom content.
   price="2.00"
   thumb="https://img.yzcdn.cn/vant/ipad.jpeg"
 >
-  <div slot="tags">
+  <template #tags>
     <van-tag plain type="danger">Tag</van-tag>
     <van-tag plain type="danger">Tag</van-tag>
-  </div>
-  <div slot="footer">
+  </template>
+  <template #footer>
     <van-button size="mini">Button</van-button>
     <van-button size="mini">Button</van-button>
-  </div>
+  </template>
 </van-card>
 ```
 

src/card/README.zh-CN.md

@@ -51,14 +51,14 @@ Vue.use(Card);
   title="商品标题"
   thumb="https://img.yzcdn.cn/vant/ipad.jpeg"
 >
-  <div slot="tags">
+  <template #tags>
     <van-tag plain type="danger">标签</van-tag>
     <van-tag plain type="danger">标签</van-tag>
-  </div>
-  <div slot="footer">
+  </template>
+  <template #footer>
     <van-button size="mini">按钮</van-button>
     <van-button size="mini">按钮</van-button>
-  </div>
+  </template>
 </van-card>
 ```