Zeki Akyol

Results 4 issues of Zeki Akyol

- It updates "R for Data Science" book url to its second edition.

- This pull request updates r4ds() to r4ds 2e (https://r4ds.hadley.nz/) on the package website. - **README.md** is updated by running `devtools::build_readme()`.

- It updates the argument `size` to `linewidth` for ggplot 3.4.0 version and afterwards.

- This pull request updates the `size` argument to `linewidth` for the appropriate plots to align with ggplot 3.4.0.