Fix training schedules in examples to match new API
Re #445:
- update examples to work with the new optimizer API
@lukovnikov do you want to give this PR a look and confirm it's fine?

Also, we should document a bit the new optimizer API in the README. Do you want to use this PR to copy a few docstring in the README (we currently don't have auto-generated doc)?<|||||>Hi. Sorry, forgot about the examples.
Did a couple fixes in my 'schedules_in_examples' branch (see PR #531).
However, I don't have the fp16 setup yet so wasn't able to run the examples to be completely sure.
Docs update is here: PR #533.<|||||>Got it.
Ok to merge this PR @lukovnikov?<|||||>With the fixes from #531, should be good.<|||||>Thanks!