Update install_linux.md (#19767)
Update install_linux.md (#19767)

* Update install_linux.md

This not necessary and adds confusion to the instruction outlined in the Docker session. The host machine only requires Nvidia drivers, not the CUDA toolkit or cuDNN.

The containers require CUDA toolkit and cuDNN to be present. See:
https://github.com/nvidia/nvidia-docker/wiki/CUDA#requirements

* Add link to the NVidia Docker requirements page.

tensorflow/docs-l10n,tensorflow/docs,tensorflow/docs,tensorflow/docs