import_roboto() tests to see if Roboto is imported and registered. If
Roboto, isn't imported and registered, then import_roboto() imports and
registers Roboto with
library(extrafont).
Details
Note: Roboto must be installed on your computer for import_roboto() to
work. Roboto is Brooking's main font. To install, visit
Google fonts and click
"Download family". Unzip and open each of the .ttf files and click install.