To cite package ‘markdown’ in publications use:

  Xie Y, Allaire J, Horner J (2024). _markdown: Render Markdown with
  'commonmark'_. R package version 1.13,
  <https://github.com/rstudio/markdown>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {markdown: Render Markdown with 'commonmark'},
    author = {Yihui Xie and JJ Allaire and Jeffrey Horner},
    year = {2024},
    note = {R package version 1.13},
    url = {https://github.com/rstudio/markdown},
  }