Co-authored-by: Eric Liang <ekhliang@gmail.com>
The package "ml" should be renamed to "air". Main question: Keep a `ml.py` with `from ray.air import *` for some level of backwards compatibility? I'd go for no to force people to use the new structure.
Following #24959, this PR moves the RL examples (online/offline/serving) into the Ray ML docs. It also splits the online and offline parts.
