update tree docs

packages/checkbox/src/checkbox.vue

@@ -30,9 +30,9 @@
         type="checkbox"
         :disabled="disabled">
     </span>
-    <span class="el-checkbox__label">
+    <span class="el-checkbox__label" v-if="$slots.default || label">
       <slot></slot>
-      <template v-if="!$slots || !$slots.default">{{label}}</template>
+      <template v-if="!$slots.default">{{label}}</template>
     </span>
   </label>
 </template>

packages/theme-default/src/tree.css

@@ -21,7 +21,7 @@
         vertical-align: middle;
       }
       & > * {
-        margin-right: 8px;
+        margin-right: 3px;
       }
       &:hover {
         background: #e5e9f2;