Update ja/translation.json

Author: jeannotdamoiseaux

app/frontend/src/locales/ja/translation.json

@@ -62,7 +62,7 @@
         "speakAnswer": "音声による回答",
         "info": "情報",
         "save": "保存",
-        "copy": "回答をコピー",
+        "copy": "コピー",
         "copied": "コピーしました！"
     },