fix: add manifest.json.example back

public/.gitignore

@@ -1,4 +1,4 @@
 *
 !.gitignore
-!manifest.json
+!manifest.json.example
 !browserconfig.xml

public/manifest.json.example

@@ -0,0 +1,14 @@
+{
+    "name": "Koel",
+    "start_url": "https://your.koel.host",
+    "display": "standalone",
+    "orientation": "portrait",
+    "icons": [{
+      "src": "/public/img/icon.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    }],
+    "background_color": "#181818",
+    "description": "Personal audio streaming service that works.",
+    "theme_color": "#181818"
+}