Beautify custom event details card

aleksis/core/frontend/components/calendar_feeds/details/CustomDetails.vue

 <template>
   <base-calendar-feed-details v-bind="$props">
     <template #description="{ selectedEvent }">
+      <v-divider
+        inset
+        v-if="selectedEvent.description && !withoutDescription"
+      />
+      <v-list-item v-if="selectedEvent.description && !withoutDescription">
+        <v-list-item-icon>
+          <v-icon color="primary">mdi-card-text-outline</v-icon>
+        </v-list-item-icon>
+        <v-list-item-content style="white-space: pre-line">
+          {{ selectedEvent.description }}
+        </v-list-item-content>
+      </v-list-item>
       <v-divider inset />
       <v-list-item v-if="selectedEvent.meta.groups.length">
         <v-list-item-icon>
@@ -34,6 +46,8 @@
           </v-list-item-title>
         </v-list-item-content>
       </v-list-item>
+    </template>
+    <template #actions>
       <v-divider inset />
       <v-card-actions>
         <custom-event-dialog