Add citing papers to FORD docs

[t-young31]

This PR adds a python script to query the ALPS ADS library for the entries and print them as a markdown file suitable for FORD to render. It's based on a script by @kgklein with a few edits: (1) Doesn't do any concat of paginated results as the API is quite happy to return 1000+ results. (2) Requests a custom export format rather than parsing bibtext to be a little more fault tolerant (3) Renders markdown instead of raw HTML, allowing FORD to do the conversion and integrate nicely.

Rendered version: https://t-young31.github.io/ALPS/page/citingpapers.html

[t-young31]

~Looks like the doc workflow is failing because the secret is not accessible on pull_request: https://securitylab.github.com/research/github-actions-preventing-pwn-requests/~

Not sure of a good solution here, other than not building the docs on PRs

edit: Chatted to @dstansby who suggested just not building that bit of the docs. Hopefully an ok solution