Add cookbooks for JSON serialization and deserialization

[gpopides]

I have added 2 new cookbook files for json serialization and deserialization. I believe this task is pretty common and would help people trying to learn the language.

I'm not an ocaml expert so i first looked myself in the cookbooks to see if there is one.

I also haven't found a PR for this, so i thought about sharing what i had to use for my needs.

I also have followed the idea of the yaml cookbook.

Any feedback would be welcome

[sabine]

Thanks @gpopides! ✨ Indeed, JSON is so common it is very useful to have this!

[christinerose]

Let me know when this is ready for my review. The ize will need to be changed to ise for OCaml.org, but I'll do all that along with the other line editing. Just ping me when you're ready, and I'll ignore the notifications before then.

[gpopides]

Let me know when this is ready for my review. The ize will need to be changed to ise for OCaml.org, but I'll do all that along with the other line editing. Just ping me when you're ready, and I'll ignore the notifications before then.

Sure, i will ping you a bit later when i will be able to adjust it based on the comments. Thanks!

[gpopides]

I have applied all of the suggestions (thanks for that) so the comments are more understandable now. Let me know if we need to adjust anything else