Update JSON_INFO.md

[RedMisao]

Summary

None

Purpose of change

Document missing stuff related to Professions, such as the recipes and spells fields, what "Hobbies" are, and the "Professions group" type. The "Professions" section can also be improved by using a block example describing what each field does and how it can be used.

Describe the solution

Update the professions section of the doc:

1. Added a block example for profession, with examples of every field that can be used. This is for the sake of clarity as it's more clear (I believe) and compact
2. Added the missing fields of recipe (added back in Professions can start with specific recipes #68818, which I found by chance) and spells (no idea when this was added)
3. Added a subsection for "Hobbies", under "Professions", with a block example
4. Added a subsection for "Profession groups", also under "Professions", explaining what it is and how it's used
5. Cleaned the Index

Describe alternatives you've considered

Testing

Additional context

1. Couldn't find an example of hobbies nor whitelist_hobbies usage anywhere, so I did not add it to the example
2. I noticed that while the doc is organized by our (contributors) work, it contains mismatch of formats and there's stuff that has been moved elsewhere or it's obsolete.
   This requires a further clean up of this doc, maybe addding a standard style/guide in JSON_STYLE.md. The former requires a lot of work given JSON_INFO.md is +6k lines and most of that can be standarized.