Update .env.prod.example for Stripe invoices (#23)

.env.prod.example

@@ -34,6 +34,18 @@ EMAIL_HOST_USER=replace-with-smtp-user
 EMAIL_HOST_PASSWORD=replace-with-smtp-password
 EMAIL_PORT=2525
 EMAIL_USE_TLS=true
+# DEFAULT_FROM_EMAIL=AI ML Operations, LLC <info@aimloperations.com>
+
+# Stripe (live keys from https://dashboard.stripe.com/apikeys)
+# Secret key starts with sk_live_; publishable with pk_live_
+STRIPE_SECRET_KEY=replace-with-stripe-secret-key
+STRIPE_PUBLISHABLE_KEY=replace-with-stripe-publishable-key
+# Dashboard → Developers → Webhooks → endpoint
+# URL: https://aimloperations.com/financial/stripe/webhook/
+# Events: invoice.paid, invoice.payment_failed, invoice.finalized,
+#         customer.subscription.updated, customer.subscription.deleted,
+#         checkout.session.completed
+STRIPE_WEBHOOK_SECRET=replace-with-stripe-webhook-signing-secret
 
 # Gunicorn
 GUNICORN_WORKERS=2