Add screenshots to PWA Manifest

static/manifest.json

@@ -5,7 +5,7 @@
   "scope": "/",
   "display": "standalone",
   "background_color": "#404c55",
-  "description": "Live station departures, PIS Code Lookup, Reference Data, Timetable search, with enhanced data for staff.",
+  "description": "Get instant access to live train data, PIS codes, and location reference codes. Built by railway staff, for railway staff – your fastest route to accurate information.",
   "categories": "travel,utilities",
   "lang": "en",
   "orientation": "portrait",
@@ -29,5 +29,43 @@
       "type": "image/png",
       "purpose": "any"
     }
+  ],
+  "screenshots": [
+    {
+      "src": "/images/screenshots/narrow-home.png",
+      "type": "image/png",
+      "form_factor": "narrow",
+      "label": "Homescreen of OwlBoard"
+    },
+    {
+      "src": "/images/screenshots/narrow-ldbs.png",
+      "type": "image/png",
+      "form_factor": "narrow",
+      "label": "Live rail departure boards"
+    },
+    {
+      "src": "/images/screenshots/narrow-timetable.png",
+      "type": "image/png",
+      "form_factor": "narrow",
+      "label": "Train details and PIS Codes"
+    },
+    {
+      "src": "/images/screenshots/wide-home.png",
+      "type": "image/png",
+      "form_factor": "wide",
+      "label": "Homescreen of OwlBoard"
+    },
+    {
+      "src": "/images/screenshots/wide-ldbs.png",
+      "type": "image/png",
+      "form_factor": "wide",
+      "label": "Live rail departure boards"
+    },
+    {
+      "src": "/images/screenshots/wide-timetable.png",
+      "type": "image/png",
+      "form_factor": "wide",
+      "label": "Train details and PIS Codes"
+    }
   ]
 }