chore: add example jwt options in example settings file

src/FiscalOS.API/appsettings.Example.json

@@ -8,5 +8,11 @@
   "AllowedHosts": "*",
   "AppDbContextOptions": {
     "DatabaseFilePath": "DatabaseFilePath"
+  },
+  "JwtOptions": {
+    "Audience": "Audience",
+    "Issuer": "Issuer",
+    "Secret": "Secret",
+    "ExpiryInMinutes": "ExpiryInMinutes"
   }
 }