Improve docs for the jsdoc-plugins package

[ma2ciek]

This package gets some traffic (#456).

We can try to improved these docs in the following way:

• List all available plugins, write which package handles which problem and if the package is CKEditor 5 related or not.
• Think of some better error messages. We can list these error messages with potential solutions.
• Create a TOC
• Link TODO to GH issues
• Improve the usage guide, write about some differences between our approach to writing docs and docs found in the http://usejsdoc.org/.

[ma2ciek]

We could also link to the umberto project as a potential package to be used later.