CDC datasets

[avahoffman]

https://www.cdc.gov/nchs/nhanes/index.htm

[carriewright11]

@avahoffman want to add this to the final projects? or to data in the class? anything you want me to add to the package? I forked john's repo

[avahoffman]

I was thinking of adding more public health-y data. Just an idea!

I added two more that could definitely go in the package:

• updated vaccination data - https://github.com/jhudsl/intro_to_r/blob/main/data/vaccinations.csv
• asthma prevalence - https://github.com/jhudsl/intro_to_r/blob/main/data/asthma.xlsx