Update Python/README.md to better comprehend MPI plugin (#1145)

Author: bmhowe23

python/README.md

@@ -47,10 +47,12 @@ Quantum with all its dependencies:
 ```console
     conda create -y -n cuda-quantum python==3.10 pip
     conda install -y -n cuda-quantum -c "nvidia/label/cuda-11.8.0" cuda
-    conda install -y -n cuda-quantum -c conda-forge mpi4py openmpi
+    conda install -y -n cuda-quantum -c conda-forge mpi4py openmpi cxx-compiler cuquantum
     conda env config vars set -n cuda-quantum LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$CONDA_PREFIX/envs/cuda-quantum/lib"
+    conda env config vars set -n cuda-quantum MPI_PATH=$CONDA_PREFIX/envs/cuda-quantum
     conda run -n cuda-quantum pip install cuda-quantum
     conda activate cuda-quantum
+    source $CONDA_PREFIX/lib/python3.10/site-packages/distributed_interfaces/activate_custom_mpi.sh
 ```
 
 [//]: # (End conda install)