Added README for HPC demo

To minimize the risk of Summit unavailability, TNQVM/ExaTN demo will be based on Andes.

DM-Sim on Summit: 1GPU demo on login node, multi-GPU live demo if interactive session available. Otherwise, just do a job submission...

Signed-off-by: Thien Nguyen <nguyentm@ornl.gov>

examples/qcor_demos/ibm_qasm3_demo_092021/qasm3-gpu-sim/README.md

+# TNQVM Random Circuit Run
+
+- Platform: Andes Cluster: 2 AMD EPYC 7302 16Core Processor 3.0 GHz, 16 cores (total 32 cores per node)
+
+- Modules
+
+```
+module load gcc/10.3.0 cmake/3.18.4 python/3.7-anaconda3 git/2.29.0 openblas/0.3.12-omp
+```
+
+- ExaTN build (MPI enabled)
+```
+CC=gcc CXX=g++ FC=gfortran cmake .. -DCMAKE_BUILD_TYPE=Release -DEXATN_BUILD_TESTS=TRUE -DBLAS_LIB=OPENBLAS -DBLAS_PATH=/sw/andes/spack-envs/base/opt/linux-rhel8-x86_64/gcc-10.3.0/openblas-0.3.12-lvqlwh4l3ywjy3fmrfcusmh2ooyt2r4b/lib -DMPI_LIB=OPENMPI -DMPI_ROOT_DIR=/sw/andes/spack-envs/base/opt/linux-rhel8-x86_64/gcc-10.3.0/openmpi-4.0.4-4gclv46mxmuq3kriamaxinzezppb7vyi -DCMAKE_INSTALL_PREFIX=/ccs/proj/phy149/Thien/.exatn
+```
+
+- XACC and TNQVM build:
+
+```
+cmake .. -DCMAKE_INSTALL_PREFIX=/ccs/proj/phy149/Thien/.xacc
+```
+
+```
+CC=gcc CXX=g++ FC=gfortran cmake .. -DCMAKE_BUILD_TYPE=Release -DXACC_DIR=/ccs/proj/phy149/Thien/.xacc -DEXATN_DIR=/ccs/proj/phy149/Thien/.exatn  -DTNQVM_BUILD_TESTS=TRUE -DTNQVM_BUILD_EXAMPLES=TRUE
+```
+
+- QCOR build
+```
+CC=gcc CXX=g++ cmake .. -DXACC_DIR=/ccs/proj/phy149/Thien/.xacc -DLLVM_ROOT=/ccs/proj/phy149/Thien/.llvm -DMLIR_DIR=/ccs/proj/phy149/Thien/.llvm/lib/cmake/mlir -DQCOR_BUILD_TESTS=TRUE -DQCOR_EXTRA_HEADERS="/sw/andes/gcc/10.3.0/include/c++/10.3.0/x86_64-pc-linux-gnu/;/sw/andes/gcc/10.3.0/include/c++/10.3.0/"
+```
+
+- Export PATH (for qcor command-line tools)
+
+```
+export PATH=/ccs/proj/phy149/Thien/.xacc/bin:$PATH
+```
+
+- Interactive session request (2 full node for 1 hour):
+
+```
+salloc -A PHYXXX -N 2 -t 1:00:00
+```
+
+- Run MPI: 4 tasks on 2 nodes, each uses 16 cores.
+
+```
+srun -n4 -N2 -c16 --cpu-bind=threads ./a.out -qrt nisq -qpu tnqvm -qpu-config tnqvm.ini
+```
+
+# DM-SIM Adder Circuit (GPU)
+
+- Platform: Summit. 
+Login node: (2) 16-core Power9 CPUs and (4) V100 GPUs. 
+Compute nodes have (2) 22-core Power9 CPUs and (6) V100 GPUs.
+
+Note: on login node, we can only use **one** GPU for testing.
+
+- Request an interactive session: 
+
+```
+bsub -Is -W 1:00 -nnodes 1 -P PHYXXX $SHELL
+```
+
+Note: small jobs (e.g., single node) is low priority (w.r.t. Summit job scheduling), hence we may not be able to request
+an allocation for the live session.
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