Add reverse proxy SSL guides for Caddy, Nginx, and Traefik.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -3,6 +3,12 @@ APP_PORT=8080
 APP_SECRET=change-me-to-a-long-random-secret-key
 APP_ENV=production
 
+# Public domain (reverse proxy / SSL)
+DOMAIN=panel.example.com
+ACME_EMAIL=admin@example.com
+# Dokploy Traefik cert resolver name (часто letsencrypt)
+TRAEFIK_CERT_RESOLVER=letsencrypt
+
 # Admin authorization
 ADMIN_EMAIL=admin@panel.local
 ADMIN_PASSWORD=Admin123!ChangeMe