Remove lesson lifecycle from lesson design episode

### 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

Open the lesson-design.html page and locate the source content for the lesson lifecycle passage. Read the surrounding lesson design and “how we operate” sections to confirm which lifecycle-stage wording should move or be removed. Done means the lesson design episode keeps the iterative-development mention without introducing the lifecycle stages too early, while the intended mention remains in the how-we-operate section.

Written by the indexing model from the issue text.