Release windfarmGA 4.0.0

[trafficonese]

First release:

• [x] usethis::use_cran_comments()
• [x] Update (aspirational) install instructions in README
• [x] Proofread Title: and Description:
• [x] Check that all exported functions have @return and @examples
• [x] Check that Authors@R: includes a copyright holder (role 'cph')
• [x] Check licensing of included files
• [x] Review https://github.com/DavisVaughan/extrachecks

Prepare for release:

• [x] git pull
• [x] Check if any deprecation processes should be advanced, as described in Gradual deprecation
• [x] urlchecker::url_check()
• [x] devtools::check(remote = TRUE, manual = TRUE)
• [x] devtools::check_win_devel()
• [x] rhub::check_for_cran()
• [x] rhub::check(platform = 'ubuntu-rchk')
• [x] rhub::check_with_sanitizers()
• [ ] git push
• [ ] Draft blog post

Submit to CRAN:

• [ ] usethis::use_version('minor')
• [ ] devtools::submit_cran()
• [ ] Approve email

Wait for CRAN...

• [ ] Accepted :tada:
• [ ] git push
• [ ] usethis::use_github_release()
• [ ] usethis::use_dev_version()
• [ ] git push
• [ ] Finish blog post
• [ ] Tweet
• [ ] Add link to blog post in pkgdown news menu