Add Paper Citations to Repos

[codyaustun]

To help keep track of how MLPerf is being used, we should ask people to cite our work. I already created PRs for the training and inference repos.

• Training paper (Please review and approve)
• Inference paper

Similar PRs would also be good for the following:

• https://github.com/mlcommons/tiny
• https://github.com/mlcommons/mlcube
• https://github.com/mlcommons/hpc

You could even include the "MLPerf: An Industry Standard Benchmark Suite for Machine Learning Performance" paper on the policies repo.

[codyaustun]

@TheKanter