The documentation for the `State` resource still referenced the use of
`apply_state_transition` to manually force a state transition to occur,
and the question around how to force transitions had come up a few times
on discord.
This is a docs-only change, that does the following:
- Properly references `StateTransition` in the `MainSchedule` docs
- replace the explanations for applying `NextState` with ones that
explain the `StateTransition` schedule, and mentions the possibility of
calling it manually
- Add an example of calling `StateTransition` manually in the docs for
the state transition schedule itself.
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Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>