Automate the mkdocs table of contents

[goneall]

See #902 (comment) for a suggestion on how to automate this.

[goneall]

cc: @rnjudge @zvr

[bact]

• For the generation part, it is now implemented in the spec-parser by Create list of files for mkdocs spec-parser#130
• Use the actual list of model entries #978 is open as a reminder for the inclusion of the generated list in the publishing pipeline.

We can probably close this issue to clean up the 3.0 milestone.

[zvr]

Yup, closing this, let's follow on the latest opened one.