Add example config

Resources/config_example.json

@@ -0,0 +1,11 @@
+{
+    "serverPort": 8000,
+    "production": false,
+    "mail": {
+        "serverDomain": "https://example.com/schafkopf",
+        "emailHostname": "example.com",
+        "email": "schafkopf@example.com",
+        "password": "some-secret-string",
+        "tokenExpiryDuration": 15,
+    }
+}