Fix duplicate string

Author: MaySoMusician

src/assets/locales/ja.json

@@ -69,7 +69,6 @@
         "date": "日付設定",
         "time": "時間設定",
         "subject_label_color": "ラベル色",
-        "description": "内容（ないよう）",
         "video_keyword": "（オプション機能）動画検索",
         "video_url": "参考動画URL",
         "video_thumbnail": "動画サムネイル・キャプション表示",

src/components/EditLessonScreenInner2.vue

@@ -6,7 +6,7 @@
     />
     <editor-textarea
       v-model="tempFormData.description"
-      :title="$t('components.editing_screen.labels.description')"
+      :title="$t('common.lesson_data.labels.description')"
     />
   </div>
 </template>