To cite deckhand in publications use:

  Kerlogue M (2022) deckhand: Create data heavy pagedown reports, Crown
  Copyright (Cabinet Office), https://github.com/co-analysis/deckhand

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {deckhand: Create data heavy pagedown reports},
    author = {Matt Kerlogue},
    year = {2022},
    organization = {Crown Copyright (Cabinet Office)},
    url = {https://github.com/co-analysis/deckhand},
  }