Release RcppDeepState 2.0

[akhikolla]

Prepare for release:

• Check that description is informative
• Check licensing of included files
• usethis::use_cran_comments()
• devtools::check(remote = TRUE, manual = TRUE)
• devtools::check_win_devel()
• rhub::check_for_cran()
• Update cran-comments.md
• Draft blog post

Submit to CRAN:

• usethis::use_version('major')
• devtools::submit_cran()
• Approve email

Wait for CRAN...

• Accepted 🎉
• usethis::use_news_md()
• usethis::use_github_release()
• usethis::use_dev_version()
• Update install instructions in README
• Finish blog post
• Tweet
• Add link to blog post in pkgdown news menu