Add translation for the page not found error

src/locales/en.json

@@ -9,6 +9,7 @@
         }
     },
     "error": {
-        "tryAgainToAnotherTime": "Please try again to another time."
+        "tryAgainToAnotherTime": "Please try again to another time.",
+        "pageNotFound": "The page you are looking for does not exist. Please check the URL or return to the search page."
     }
 }