feat(ActionSheet): add description prop (#4691)

src/action-sheet/test/__snapshots__/demo.spec.js.snap

@@ -14,5 +14,8 @@ exports[`renders demo correctly 1`] = `
   <div><button class="van-button van-button--primary van-button--normal"><span class="van-button__text">弹出菜单</span></button>
     <!---->
   </div>
+  <div><button class="van-button van-button--primary van-button--normal"><span class="van-button__text">弹出菜单</span></button>
+    <!---->
+  </div>
 </div>
 `;

src/action-sheet/test/__snapshots__/index.spec.js.snap

@@ -8,6 +8,12 @@ exports[`callback events 1`] = `
 
 exports[`color option 1`] = `<div class="van-popup van-popup--round van-popup--bottom van-popup--safe-area-inset-bottom van-action-sheet" name="van-popup-slide-bottom"><button class="van-action-sheet__item van-hairline--top" style="color: red;"><span class="van-action-sheet__name">Option</span></button></div>`;
 
+exports[`description prop 1`] = `
+<div class="van-popup van-popup--round van-popup--bottom van-popup--safe-area-inset-bottom van-action-sheet" name="van-popup-slide-bottom">
+  <div class="van-action-sheet__description">This is a description</div><button class="van-action-sheet__item van-hairline--top"><span class="van-action-sheet__name">Option</span></button>
+</div>
+`;
+
 exports[`disable lazy-render 1`] = `<div class="van-popup van-popup--round van-popup--bottom van-popup--safe-area-inset-bottom van-action-sheet" style="display: none;" name="van-popup-slide-bottom"><button class="van-action-sheet__item van-hairline--top"><span class="van-action-sheet__name">Option</span></button><button class="van-action-sheet__item van-hairline--top"><span class="van-action-sheet__name">Option</span></button><button class="van-action-sheet__cancel">Cancel</button></div>`;
 
 exports[`render title and default slot 1`] = ``;

src/action-sheet/test/index.spec.js

@@ -162,3 +162,15 @@ test('color option', () => {
 
   expect(wrapper).toMatchSnapshot();
 });
+
+test('description prop', () => {
+  const wrapper = mount(ActionSheet, {
+    propsData: {
+      value: true,
+      description: 'This is a description',
+      actions: [{ name: 'Option' }]
+    }
+  });
+
+  expect(wrapper).toMatchSnapshot();
+});