fix: Add labels and about section

public/i18n/de.json

@@ -11,6 +11,9 @@
   "result": "Ergebnis",
   "number-of-rats": "Anzahl an Ratten",
   "change-language": "Sprache ändern",
+  "about": "Über uns",
+  "imprint": "Impressum",
+  "source-code": "Quellcode",
   "failed-base-area": "Die Mindestgrundfläche des Käfigs muss {{ MINIMUM_BASE_AREA }}m² (also z.B. 100x50cm) betragen.",
   "failed-overall-area": "Die Gesamtfläche im Käfig ist zu klein.",
   "failed-fall-height": "Die mögliche Fallhöhe darf nicht mehr als {{ maximum_fall_height }}cm betragen.",

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.",