docs: Add slurm env var workaround for MPI spawn errors (#992)

examples/tensorrt_llm/README.md

@@ -197,6 +197,14 @@ Notes:
   cd /workspace/examples/tensorrt_llm
   dynamo serve components.worker:TensorRTLLMWorker -f ./configs/disagg.yaml --service-name TensorRTLLMWorker &
   ```
+- If you see an error about MPI Spawn failing during TRTLLM Worker initialziation on a Slurm-based cluster,
+  try unsetting the following environment variables before launching the TRTLLM worker. If you intend to
+  run other slurm-based commands or processes on the same node after deploying the TRTLLM worker, you may
+  want to save these values into temporary variables and then restore them afterwards.
+  ```bash
+  # Workaround for error: `mpi4py.MPI.Exception: MPI_ERR_SPAWN: could not spawn processes`
+  unset SLURM_JOBID SLURM_JOB_ID SLURM_NODELIST
+  ```
 
 ### Client