Update template pytorch dockerfile with cuda sync memops stanza

2.ami_and_containers/containers/pytorch/0.nvcr-pytorch-aws.dockerfile

@@ -23,11 +23,15 @@ FROM nvcr.io/nvidia/pytorch:23.12-py3
 ENV DEBIAN_FRONTEND=noninteractive
 
 # The three must-be-built packages.
-# Efa-installer>=1.29.0 required for nccl>=2.19.0 to avoid libfabric NCCL error.
+# Efa-installer>=1.29.1 required for nccl>=2.19.0 to avoid libfabric NCCL error.
 ENV EFA_INSTALLER_VERSION=1.30.0
 ENV AWS_OFI_NCCL_VERSION=1.8.1-aws
 ENV NCCL_TESTS_VERSION=master
 
+## Uncomment below when this Dockerfile builds a container image with efa-installer<1.29.1 and
+# nccl>=2.19.0. See https://github.com/aws-samples/awsome-distributed-training/tree/main/1.architectures/efa-cheatsheet.md
+#ENV FI_EFA_SET_CUDA_SYNC_MEMOPS=0
+
 RUN apt-get update -y
 RUN apt-get remove -y --allow-change-held-packages \
                       libmlx5-1 ibverbs-utils libibverbs-dev libibverbs1