Day 2: Functions Defined as Data Type

[Mroussell]

In the Day 2 markdown file, "02_day_data_types.md". Functions are labeled as a non-primitive data type in this markdown file. Functions are themselves callable objects in javascript. As this is a tutorial for beginners, it might be best to leave functions out of that definition. Labeling functions in this way is not completely true and could cause confusion. A good alternative may be labeling the special data types, null and undefined, and having an objects section where it is explained that objects include functions, arrays, maps, and so on.

This is merely a suggestion, hope it is helpful.
Thank you!