Update docs

[wooorm]

Hi! 👋

Some of these plugins are very interesting (I especially like deflist and bilbiography) and may be useful outside of markbook.
Some of the docs aren’t very detailed though.

If you’d like, could you update the docs, and when done, create a PR to add them to the list of plugins?

[Symbitic]

@wooorm Hi. Sorry for taking so long to get back. I recently updated several packages, especially deflist and bibliography. The documentation is included in the README for each package. I updated the docs for deflist and bibliography; if those look good to you, I'll create a PR.

[wooorm]

Heya! 👋

Hmm, remark-parse changed a lot in v9, and this project seems to be on remark-parse 7. So it would be nice to test on latest remark packages before that PR!