fix: Add labels and about section

public/i18n/en.json

@@ -11,6 +11,9 @@
   "result": "Result",
   "number-of-rats": "Number of Rats",
   "change-language": "Change language",
+  "about": "",
+  "imprint": "Imprint",
+  "source-code": "Source Code",
   "failed-base-area": "The base area of the cage must not be below {{ MINIMUM_BASE_AREA }}m².",
   "failed-overall-area": "The overall area in the cage is to small.",
   "failed-fall-height": "The possible fall height between floors must not be above {{ maximum_fall_height }}cm.",