Drop --token from the hand-started worker examples

The worker reads FLUKSIO_WORKER_TOKEN itself; on the command line the
token shows in ps. The --token row in the options table says so.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013GAeg4Jo6xjZzjwy9QDWMQ

worker/README.md

@@ -9,7 +9,6 @@ pip install fluksio-worker
 
 fluksio-worker \
   --url wss://api.example.com/api/v1/workers/attach \
-  --token "$FLUKSIO_WORKER_TOKEN" \
   --labels gpu,cuda12 \
   --python /opt/torch-venv/bin/python
 ```

worker/fluksio_worker/agent.py

@@ -3,8 +3,7 @@
 Point it at the engine on the box with the GPU and it dials in::
 
     pip install fluksio-worker
-    fluksio-worker --url wss://api.example.com/api/v1/workers/attach \\
-        --token "$FLUKSIO_WORKER_TOKEN" --labels gpu
+    fluksio-worker --url wss://api.example.com/api/v1/workers/attach --labels gpu
 
 Install it into the environment the training code already runs in and node
 code runs on that: ``--python`` defaults to the interpreter this was started