Add button that allows user to export the bibtex and RIS (endnote) citation

[amyheather]

Feature request from @TomMonks

He suggested could just hardcode

At present, citations are generated by Quarto (https://quarto.org/docs/authoring/create-citeable-articles.html).

I've set in _metadata.yml:

# Type: article-journal required so container-title is registered as journal name
citation:
  type: article-journal

# At end of page, generate BibTex and display version of citation
appendix-cite-as: true

Then in YAML for each publication page I have:

title: "Building healthcare discrete-event simulation models in free and open source software: an introductory tutorial"
doi: 10.36819/SW25.004
author:
  - name: Thomas Monks
    affiliation: University of Exeter Medical School
    orcid: 0000-0003-2631-4481
  - name: Alison Harper
    affiliation: University of Exeter Business School
    orcid: 0000-0001-5274-5037
  - name: Amy Heather
    affiliation: University of Exeter Medical School
    orcid: 0000-0002-6596-3479
  - name: Andrew Mayne
    affiliation: Somerset NHS Foundation Trust
    orcid: 0000-0003-1263-2286
  - name: Navonil Mustafee
    affiliation: University of Exeter Business School
    orcid: 0000-0002-2204-8924
date: 31 March 2025
citation:
  container-title: "Proceedings of the Operational Research Society Simulation Workshop 2025 (SW25)"
image: frontpage.png
categories:
  - Tutorial