docs: say how to get a released worker

Neither the image nor the release tarballs were mentioned; a toolchain and a
cargo build read as the only way in.

Claude-Session: https://claude.ai/code/session_01Rkp1Mw5E89Jp6dzJFYiMrm

seaweed-worker/README.md

@@ -20,6 +20,22 @@ The admin's *HTTP* address is what an operator has; the gRPC port is derived
 from it the way the Go side does. Dialling the HTTP port fails as "frame with
 invalid size", which reads like a protocol bug rather than a wrong port.
 
+The binary is `weed-worker`, not `weed-lance-worker`: it is the Rust side of
+`weed worker`, and lance is the first family of jobs it carries rather than the
+only one it ever will.
+
+Released builds do not need a toolchain. The worker ships inside the SeaweedFS
+image, beside the Rust volume server, under the verb that mirrors
+`volume-rust`:
+
+    docker run chrislusf/seaweedfs worker-rust --admin admin:23646
+
+and as `weed-worker_linux_{amd64,arm64}.tar.gz` on each GitHub release. Both are
+linux amd64/arm64 only — lance, arrow and datafusion make every extra target an
+expensive build, and the worker runs beside the cluster it maintains. On an
+architecture without a build the image carries an empty placeholder and the
+entrypoint says so rather than failing as "not found".
+
 ## Metrics
 
     cargo run -p weed-lance-worker -- --admin 127.0.0.1:23646 --metrics-port 9328