Consistently refer to plans by consistent names

https://github.com/CodeYourFuture/Module-Structuring-and-Testing-Data/issues/9 refers to a Build Your Life plan and a Career Development plan.

The previous courseworks (https://github.com/CodeYourFuture/Module-User-Focused-Data/issues/59, https://github.com/CodeYourFuture/Module-User-Focused-Data/issues/51, https://github.com/CodeYourFuture/Module-User-Focused-Data/issues/53, https://github.com/CodeYourFuture/Module-User-Focused-Data/issues/49) refer to these with different names.

We should pick consistent names for these plans, and refer to them thus, rather than using lots of different terms to refer to them. I wasn't sure, on first read, whether "Build Your Life Plan" was referring to the "Life as a developer" plan or the "Development plan".

/cc @kfklein15