[Doc] beautify demo

packages/button/demo/index.vue

@@ -78,10 +78,30 @@
     </demo-block>
 
     <demo-block :title="$t('size')">
-      <van-button size="large">{{ $t('large') }}</van-button>
-      <van-button size="normal">{{ $t('normal') }}</van-button>
-      <van-button size="small">{{ $t('small') }}</van-button>
-      <van-button size="mini">{{ $t('mini') }}</van-button>
+      <van-button
+        type="primary"
+        size="large"
+      >
+        {{ $t('large') }}
+      </van-button>
+      <van-button
+        type="primary"
+        size="normal"
+      >
+        {{ $t('normal') }}
+      </van-button>
+      <van-button
+        type="primary"
+        size="small"
+      >
+        {{ $t('small') }}
+      </van-button>
+      <van-button
+        type="primary"
+        size="mini"
+      >
+        {{ $t('mini') }}
+      </van-button>
     </demo-block>
   </demo-section>
 </template>

packages/button/en-US.md

@@ -63,10 +63,10 @@ Vue.use(Button);
 ### Size
 
 ```html 
-<van-button size="large">Large</van-button>
-<van-button size="normal">Normal</van-button>
-<van-button size="small">Small</van-button>
-<van-button size="mini">Mini</van-button>
+<van-button type="primary" size="large">Large</van-button>
+<van-button type="primary" size="normal">Normal</van-button>
+<van-button type="primary" size="small">Small</van-button>
+<van-button type="primary" size="mini">Mini</van-button>
 ```
 
 ## API

packages/button/test/__snapshots__/demo.spec.js.snap

@@ -14,6 +14,14 @@ exports[`renders demo correctly 1`] = `
       <div class="van-loading van-loading--spinner"><span class="van-loading__spinner van-loading__spinner--spinner" style="width: 20px; height: 20px;"><i></i><i></i><i></i><i></i><i></i><i></i><i></i><i></i><i></i><i></i><i></i><i></i></span></div><span class="van-button__loading-text">加载中...</span>
     </button></div>
   <div><button class="van-button van-button--primary van-button--normal van-button--square"><span class="van-button__text">方形按钮</span></button> <button class="van-button van-button--danger van-button--normal van-button--round"><span class="van-button__text">圆形按钮</span></button></div>
-  <div><button class="van-button van-button--default van-button--large"><span class="van-button__text">大号按钮</span></button> <button class="van-button van-button--default van-button--normal"><span class="van-button__text">普通按钮</span></button> <button class="van-button van-button--default van-button--small"><span class="van-button__text">小型按钮</span></button> <button class="van-button van-button--default van-button--mini"><span class="van-button__text">迷你按钮</span></button></div>
+  <div><button class="van-button van-button--primary van-button--large"><span class="van-button__text">
+      大号按钮
+    </span></button> <button class="van-button van-button--primary van-button--normal"><span class="van-button__text">
+      普通按钮
+    </span></button> <button class="van-button van-button--primary van-button--small"><span class="van-button__text">
+      小型按钮
+    </span></button> <button class="van-button van-button--primary van-button--mini"><span class="van-button__text">
+      迷你按钮
+    </span></button></div>
 </div>
 `;

packages/button/zh-CN.md

@@ -73,10 +73,10 @@ Vue.use(Button);
 支持`large`、`normal`、`small`、`mini`四种尺寸，默认为`normal`
 
 ```html 
-<van-button size="large">大号按钮</van-button>
-<van-button size="normal">普通按钮</van-button>
-<van-button size="small">小型按钮</van-button>
-<van-button size="mini">迷你按钮</van-button>
+<van-button type="primary" size="large">大号按钮</van-button>
+<van-button type="primary" size="normal">普通按钮</van-button>
+<van-button type="primary" size="small">小型按钮</van-button>
+<van-button type="primary" size="mini">迷你按钮</van-button>
 ```
 
 ## API