* fix: makes types DocusaurusConfig optional to match docs
* add UserDocusaurusConfig with required keys for user config
* convert UserDocusaurusConfig to use util type
* Docusaurus website config should be type-checked by CI + fix all existing issues
* add doc for config typechecking
* Update template configs for TS autocompletion
* fix last config typechecking bugs
* reapply prettier
* reapply prettier-docs
* Fix TS doc: add missing ()
* fix some docu plugin types
* add "const config" for simpler jsdoc annotation
Co-authored-by: slorber <lorber.sebastien@gmail.com>