Provide more examples to connect theory with practice/exercises

### How could the content be improved?

Provide more examples of exactly what we will be doing at each stage of the process, and more examples generally e.g. by discussing how considerations of expertise level might be captured in your description of target audience.

Related to #364.

### Which part of the content does your suggestion apply to?

Affects the lesson design episode & all episodes about the design process

Start with the lesson design episode and the episodes covering the design process, then compare how each stage and target-audience considerations are currently explained. Done means adding concrete practice examples for the stages and broader examples showing how expertise level can be captured in a target-audience description.

Written by the indexing model from the issue text.