deploy: the compose file names its own release, and the cut moves it with the version

deploy/docker/compose.yaml

@@ -1,10 +1,11 @@
 services:
   nxdns:
-    # Published multi-architecture image. Pin an exact version in production:
-    # NXDNS_VERSION=0.0.1 docker compose up -d. To run a locally built image
-    # instead, build it first (see deploy/docker/Dockerfile) and set
-    # NXDNS_IMAGE=nxdns.
-    image: ${NXDNS_IMAGE:-git.mial.net/mokhtar/nxdns:${NXDNS_VERSION:-latest}}
+    # Published multi-architecture image. The default is the release this file
+    # is tagged with: `zig build cut` moves it in the bump commit, so the file
+    # from a tag runs that tag's image. NXDNS_VERSION picks another release. To
+    # run a locally built image instead, build it first (see
+    # deploy/docker/Dockerfile) and set NXDNS_IMAGE=nxdns.
+    image: ${NXDNS_IMAGE:-git.mial.net/mokhtar/nxdns:${NXDNS_VERSION:-0.0.22}}
     restart: unless-stopped
     # `run --config` makes the file the sole source of configuration: nxdns
     # reconciles the database onto ./etc-nxdns/config.zon at every start, and