アイヌ語追加 (#428) (#433)

Reviewed-on: #433
Co-authored-by: miteruzo <miteruzo@naver.com>

frontend/src/locales/ja/help.json

@@ -0,0 +1,5 @@
+{
+  "title": "ヘルプ", "search": "ヘルプ検索", "history": "ヘルプ改定履歴",
+  "effectiveSince": "有効開始年月日", "empty": "該当する記事がありません．",
+  "diffTitle": "ヘルプ 差分: {{title}}", "articleTitle": "{{title}} ヘルプ"
+}