fix(theme): edit link gets hidden when a page don't have siblings (#751)

Co-authored-by: Kia Ishii <kia.king.08@gmail.com>

src/client/theme-default/components/VPDocFooter.vue

@@ -19,7 +19,7 @@ const hasLastUpdated = computed(() => {
 </script>
 
 <template>
-  <footer v-if="control.prev || control.next" class="VPDocFooter">
+  <footer class="VPDocFooter">
     <div class="edit-info">
       <div v-if="theme.editLink && frontmatter.editLink !== false" class="edit-link">
         <VPLink class="edit-link-button" :href="editLink.url" :no-icon="true">
@@ -33,7 +33,7 @@ const hasLastUpdated = computed(() => {
       </div>
     </div>
 
-    <div class="prev-next">
+    <div v-if="control.prev || control.next" class="prev-next">
       <div class="pager">
         <a v-if="control.prev" class="pager-link prev" :href="normalizeLink(control.prev.link)">
           <span class="desc">Previous page</span>