add back AnVIL version of index.Rmd

[KatherineCox]

This file got written over in the reset; this PR reverts it to the AnVIL version.

Actually, the AnVIL version also had a knitr::write_bib() code chunk. It was there because it used to be in the OTTR_Template index.Rmd, but it's now been removed from OTTR_Template. I assume from the name and comment that it builds a bibliography of any packages that are used in the book...not sure how useful that is for AnVIL books since I don't think we're likely to be using much R. I think delete it? I left it out of this PR, but can add it back.

# automatically create a bib database for R packages
knitr::write_bib(c(
  .packages(), "bookdown", "knitr", "rmarkdown"
), "packages.bib")

Also, this brought up #45, but I added that as a separate issue from this PR.

[github-actions]

Re-rendered previews from the latest commit:

• See preview of Bookdown here
• See preview of Coursera/Leanpub version here
• Download the preview of .docx file

Updated at 2022-03-04 with changes from a3d5eab

[github-actions]

No spelling errors! 🎉
Comment updated at 2022-03-04 with changes from a3d5eab

[github-actions]

No broken URLs detected! 🎉
Comment updated at 2022-03-04 with changes from a3d5eab

[avahoffman]

LGTM! Thanks for re-adding this!