fix path of manifest file

Author: Ritika Mishra

public/manifest.json

@@ -0,0 +1,13 @@
+{
+  "name": "Chords",
+  "short_name": "Chords",
+  "start_url": ".",
+  "display": "standalone",
+  "icons": [
+    { "src": "chords-logo-192x192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "chords-logo-512x512.png", "sizes": "512x512", "type": "image/png" }
+  ],
+  "screenshots": [
+    { "src": "screenshot-chords.png", "sizes": "1280x720", "type": "image/png", "form_factor": "wide" }
+  ]
+}