docs/mining: 'source the venv' instead of 'pip install --user submitit'

Mirror the cluster_training.md change — setup_container.sh install
already lands submitit in the venv, and sourcing the venv on login
makes it importable. No --user bootstrap needed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: 2 people

docs/mining.md

@@ -145,9 +145,9 @@ python3 scripts/submit_cluster.py \
         vec.backend=Serial
 ```
 
-See [`docs/cluster_training.md`](cluster_training.md) for one-time setup of
-the login-side submitit (`python3 -m pip install --user submitit pyyaml
-cloudpickle`).
+Source the venv before invoking `submit_cluster.py` (`source
+/scratch/$USER/venvs/pufferdrive/bin/activate`) — see
+[`docs/cluster_training.md`](cluster_training.md) for the rationale.
 
 Outputs land on `/scratch`; pull them down with `rsync` for in-browser viewing.