Release roxygen2md 1.0.0

[krlmlr]

Prepare for release:

• [x] Check that description is informative
• [x] Check licensing of included files
• [x] usethis::use_cran_comments()
• [x] devtools::check()
• [x] devtools::check_win_devel()
• [x] rhub::check_for_cran()
• [x] Polish pkgdown reference index
• [ ] Draft blog post

Submit to CRAN:

• [x] usethis::use_version('major')
• [x] Update cran-comments.md
• [x] devtools::submit_cran()
• [x] Approve email

Wait for CRAN...

• [x] Accepted :tada:
• [x] usethis::use_github_release()
• [x] usethis::use_dev_version()
• [x] usethis::use_news()
• [x] Update install instructions in README
• [ ] Finish blog post
• [ ] Tweet
• [ ] Add link to blog post in pkgdown news menu

[IndrajeetPatil]

Since {roxygen2md} 1.0.0 is on CRAN, I think this can be closed?