Document and log the Caddyfile autosave path

The generated Caddyfile is saved to Caddyfile.autosave inside Caddy's
config directory, but users had no way to discover this. Now the path is:
- Logged once at startup in the existing "Start" log line
- Documented in a new README section

Closes #745

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: lucaslorentz

README.md

@@ -550,6 +550,14 @@ CADDY_DOCKER_NO_SCOPE=<bool, default scope used>
 
 Check **examples** folder to see how to set them on a Docker Compose file.
 
+## Viewing the generated Caddyfile
+
+The generated Caddyfile is automatically saved to `Caddyfile.autosave` inside Caddy's config directory whenever it changes. The full path is logged at startup and depends on the environment (typically `/config/caddy/Caddyfile.autosave` in Docker). You can inspect it to troubleshoot label-to-Caddyfile conversion issues:
+
+```sh
+docker exec <caddy-container> cat /config/caddy/Caddyfile.autosave
+```
+
 ## Docker images
 Docker images are available at Docker hub:
 https://hub.docker.com/r/lucaslorentz/caddy-docker-proxy/

loader.go

@@ -158,6 +158,7 @@ func (dockerLoader *DockerLoader) Start() error {
 		zap.Strings("DockerSockets", dockerLoader.options.DockerSockets),
 		zap.Strings("DockerCertsPath", dockerLoader.options.DockerCertsPath),
 		zap.Strings("DockerAPIsVersion", dockerLoader.options.DockerAPIsVersion),
+		zap.String("CaddyfileAutosavePath", CaddyfileAutosavePath),
 	)
 
 	ready := make(chan struct{})