Minor Changes on Serialization

[khoramism]

Hey, Hope you guys are doing alright, I was reading the serialization part and i realized that we don't have much learning resources on Protocol Buffers and Avro, So the first commit is minor changes there.

I've also added the Json Schema in the Serialization Concept, Since it's being widely used in validation and serialization I felt it would be a shame not to have it on our wiki, I also checked the roadmap and we only have json there, do you guys think I should add it to there as well?

I'd very much appreciate your feedback on this pr, thanks :)

-Alireza

[niyushabaghayi]

Hi Alireza,
Thanks for your invaluable PR!
According to chapter 4 (Encoding and Evolution) of the book Designing Data-Intensive Applications, all these are "formats of encoding data." However, unlike Avro and Protocol Buffers, JSON Schema is not a serialization format. JSON itself is the serialization format, while JSON Schema is a schema validation tool used to describe and validate the structure of data already encoded in JSON.
It may be more appropriate to include JSON Schema in the JSON section rather than under Serialization as a separate section.
Additionally, because XML Schema (XSD) works similarly to XML, it might also be nice to mention it beside XML.
What do you think?

PS, also thanks for adding resources for other documents :)) I have some comments there.