feat:增加返回顶部组件

docs/.vitepress/theme/components/MyLayout.vue

@@ -12,6 +12,10 @@
           <template #doc-before>
             <ArticleMetadat />
           </template>
+
+          <template #doc-footer-before>
+            <Backtotop />
+          </template>
         </DefaultTheme.Layout>
       </div>
     </Transition>
@@ -21,6 +25,7 @@
 <script setup lang="ts">
 import DefaultTheme from 'vitepress/theme'
 import ArticleMetadat from './ArticleMetadata.vue';
+import Backtotop from './Backtotop.vue';
 import Loading from './Loading.vue';
 import { ref, onMounted } from 'vue'