add testing section to readme

README.md

@@ -43,6 +43,7 @@ docker/
     Dockerfile
     garage.toml
     .env.keys
+tests/                 # pytest integration tests (run post-deploy)
 .gitea/workflows/      # Per-app deploy workflows + provision.yml
 ```
 
@@ -160,6 +161,21 @@ docker exec garage /garage layout apply --version 1
 If only hantim is reprovisioned, argento retains the layout and hantim
 reconnects automatically.
 
+## Testing
+
+Tests live in `tests/` and run with pytest:
+
+```bash
+pip install pytest
+pytest tests/ -v
+```
+
+Tests auto-discover sites from `docker/nginx/conf.d/*.conf` — no list to
+maintain when adding new sites.
+
+The `deploy-nginx.yml` workflow runs tests automatically after each nginx
+deploy. If tests fail, Gitea sends an email notification.
+
 ## Secrets
 
 ### Bitwarden Secrets Manager