docs(card): fix usage example for vue (#23535)

Author: liamdebeasi

core/src/components/card/readme.md

@@ -250,12 +250,12 @@ export class CardExample {
 </template>
 
 <script>
-import { IonCard, IonCardContent, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel } from '@ionic/vue';
+import { IonCard, IonCardContent, IonCardHeader, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel } from '@ionic/vue';
 import { pin, walk, warning, wifi, wine } from 'ionicons/icons';
 import { defineComponent } from 'vue';
 
 export default defineComponent({
-  components: { IonCard, IonCardContent, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel }
+  components: { IonCard, IonCardContent, IonCardHeader, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel }
   setup() {
     return { warning };
   }

core/src/components/card/usage/vue.md

@@ -49,12 +49,12 @@
 </template>
 
 <script>
-import { IonCard, IonCardContent, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel } from '@ionic/vue';
+import { IonCard, IonCardContent, IonCardHeader, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel } from '@ionic/vue';
 import { pin, walk, warning, wifi, wine } from 'ionicons/icons';
 import { defineComponent } from 'vue';
 
 export default defineComponent({
-  components: { IonCard, IonCardContent, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel }
+  components: { IonCard, IonCardContent, IonCardHeader, IonCardSubtitle, IonCardTitle, IonIcon, IonItem, IonLabel }
   setup() {
     return { warning };
   }