Outdated documentation for loggers
Custom logger example doesn't work:
https://pytorch-lightning.readthedocs.io/en/latest/loggers.html#custom-logger
General loggers example doesn't work either due to missing parameters for the loggers.* class constructors:
https://pytorch-lightning.readthedocs.io/en/latest/pytorch_lightning.loggers.html#module-pytorch_lightning.loggers