Update file build.txt

MLPerf/training/image_segmentation/pytorch/build.txt

+https://catalog.ngc.nvidia.com/orgs/nvidia/resources/nnunet_for_pytorch/quick-start-guide
+
+apptainer build containers/nvidia_pytorch_21.11-py3.sif  docker://nvcr.io/nvidia/pytorch:21.11-py3
+
+export APPTAINER_BINDPATH=
+
+MODULE_NAME=nnunet_for_pytorch
+MODULE_VERSION=21.11.0
+CONTAINER_DIR=/proj/nsc_testing/xuan/containers/${MODULE_NAME}_${MODULE_VERSION}.sif
+DEF_DIR=/proj/nsc_testing/xuan/berzelius-benchmarks/PyTorch/Segmentation/nnUNet/${MODULE_NAME}_${MODULE_VERSION}.def
+
+apptainer build $CONTAINER_DIR $DEF_DIR
+
+
+# Known issue 
+https://github.com/NVIDIA/DeepLearningExamples/issues/1113