Descriptive Titles

[brymz]

(subissue #1)

'Graphing 3' used to be called 'Graphing adult size vs newborn size'. Simplifying the descriptive title to a number made me wonder if all of the problems should have a descriptive title. The descriptive title would identify the new problem/solution presented in the exercise. One of the strings exercises might get a descriptive title of 'Basic stringr functions'. A making choices exercise might get a descriptive title of 'Using mathematical operators' or 'if else statements'.

I think it makes sense to organize the directory using the current Name-X 'titles' and add a 'descriptive title' or 'subtitle' to the exercise yaml.