docs(security): remove SSH username/host specifics from public docs

.gitea/workflows/deploy.yml

@@ -9,7 +9,7 @@ on:
 #   REGISTRY            registry hostname (git.librete.ch)
 #   REGISTRY_USER       robot account or PAT username (libretech-bot)
 #   REGISTRY_PASS       PAT with write:package
-#   DEPLOY_HOST         SSH target, e.g. root@cloud.librete.ch
+#   DEPLOY_HOST         SSH target, e.g. user@your-deploy-host
 #   DEPLOY_KEY          passphrase-less private key (PEM)
 #   DEPLOY_PATH         remote stack dir (/srv/librenotes)
 #   HEALTH_URL          https://ln.cloud.librete.ch/healthz