Remove lesson lifecycle from lesson design episode

[sstevens2]

How could the content be improved?

Think the lesson life cycle might be better only mentioned in the how we operate section. We could keep the mention of iterative development but remove the mention of the lifecycle stages as that seems a bit early and in depth to mention at that point.

Which part of the content does your suggestion apply to?

https://carpentries.github.io/lesson-development-training/lesson-design.html

[tobyhodges]

I feel like we added it in after we got feedback that it should be talked about earlier?

[Update: indeed, I opened #298 in response to feedback and discussion summarised in #108.]