Update benchmark logs

[guarin]

We report tensorboard logs for our ImageNet benchmarks in the docs: https://docs.lightly.ai/self-supervised-learning/getting_started/benchmarks.html#imagenet

Sadly, tensorboard dev, where our logs are hosted, is shutting down. We should find an alternative to make the logs easily accessible. One option would be to share the tensorboard log files but this is less convenient as the plots are not readily available. Other options would be to host the logs on a different platform (wandb etc.) or provide plots ourselves (save logs as csv and add plotting script).