web: Added more information to the PWA manifest

dist/web/source/manifest.json

@@ -1,5 +1,13 @@
 {
     "name": "ImHex",
+    "description": "🔍 A Hex Editor for Reverse Engineers, Programmers and people who value their retinas when working at 3 AM.",
+    "background_color": "#0F0F0F",
+    "theme_color": "#0F0F0F",
+    "categories": [
+        "education",
+        "productivity",
+        "utilities"
+    ],
     "icons": [
         {
             "src": "icon.png",