fix: use full semver when substituting toolkit version in docs

[cdesiniotis]

The toolkit install guide is currently broken because the following command:

$ export NVIDIA_CONTAINER_TOOLKIT_VERSION=1.20-1
  sudo apt-get install -y \
      nvidia-container-toolkit=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      nvidia-container-toolkit-base=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      libnvidia-container-tools=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      libnvidia-container1=${NVIDIA_CONTAINER_TOOLKIT_VERSION}

should be:

$ export NVIDIA_CONTAINER_TOOLKIT_VERSION=1.20.0-1
  sudo apt-get install -y \
      nvidia-container-toolkit=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      nvidia-container-toolkit-base=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      libnvidia-container-tools=${NVIDIA_CONTAINER_TOOLKIT_VERSION} \
      libnvidia-container1=${NVIDIA_CONTAINER_TOOLKIT_VERSION}

[github-actions]

Documentation preview

https://nvidia.github.io/cloud-native-docs/review/pr-470