Document the format of veda-tags.json

[olejandro]

I'm wondering if we should document somewhere the format of veda-tags.json, the allowed fields and their default values? The tricky thing is how to do it in a way that we remember to keep up to date when we modify the code... I would have suggested a comment at the top of the file itself, but JSON doesn't allow comments 😅 (another little reason to use YAML!), perhaps in the function in datatypes.py that reads the file in?

Originally posted by @siddharth-krishna in #292 (review)

[olejandro]

How about defining a schema for it and then testing agains it in our unit tests?
I found an example here.

[siddharth-krishna]

Great idea! I think editors like VS Code can also pick up schemas and show errors when you're editing the file. :)