Fix errors in documentation, use DocumenterCitations.jl.

[Datseris]

Alrightly, at the moment there are some failures in our docbuilds.

For now, I have set warnonly = true to the build_docs_with_style command in docs/make.jl, so that errors in the docs do not prevent the doc build. To fix the errors, remove the warnonly = true and then see the error mssages and fix them. For example, some @example blocks are broken.

Additionally, we should port this library to use DocumenterCitations.jl just like we do in e.g., Attractors.jl. This means:

1. Add a .bib file where citations are added as bibtex
2. Change all the citation commands from [^name] to [CitationKey](@cite) and add CitationKey bibtex entry. (www.doi2bib.org can help)
3. Enable the bib in the doc build, which means to uncommented the code I Have commended in docs/make.jl.