Change bibtex example

[Omikhleia]

This is a proposal to change our bibliography example, to something more appropriate to digital typesetting, and showing the new CSL features (= SILE v0.15.7 (LuaJIT 2.1.1731601260) [Rust])

[Omikhleia]

N.B. Fails to compile on a "stock" SILE setup because of sile-typesetter/sile#2199

[alerque]

For some reason GitHub is in a funk and in spite of showing me the green check for "Maintainers are allowed to edit this pull request", it is totally blocking me from pushing to your branch or even fetching your fork over SSH. I can fetch it over HTTPS but I can't authenticate to push to that. Unless you did something weird after you forked to change the repo permissions I don't think this is your fault, GH has some infrastructure issue.

Anyhow the only thing I was going to do was add devel = true to the bibtex entry in the examples.toml file so that this sample will build with the latest master branch until we get v0.15.9 out. I'll probably go see if I can fix the site build issues, and if I can then I'll just merge this commit and add the devel flag locally afterwards.