milestone 20: declarative configuration for iac

docs/how-to/enable-doh-and-dot.md

@@ -62,10 +62,12 @@ to:
 }
 ```
 
-Write that to `/tmp/nxdns-lab/etc/config.zon`. The configuration file seeds an
-empty database and is then ignored; to change these settings on a server that
-already has a database, edit them through the API or through
-`export`/`import` — see [the configuration model](../explanation/configuration-model.md).
+Write that to `/tmp/nxdns-lab/etc/config.zon`. The lab runs
+`nxdns run --config`, which makes that file the configuration: every start
+reconciles the database onto it, so editing the file and restarting is how these
+settings change here. A real install may instead run bare `nxdns run` and keep
+the configuration in the database — see
+[the configuration model](../explanation/configuration-model.md).
 
 ## 3. Check the files before starting