Add release notes

[pedrorijo91]

Hey,

It would be really useful to understand what's new between each version to have release notes for each release.

Thanks,
Pedro

[billoneil]

You can find all the commits per release here https://github.com/jOOQ/jOOL/milestone/12?closed=1 in the short term.

[pedrorijo91]

yes, the other possibility is to use version-0.9.12...version-0.9.13

but none of them are very friendly (a short summary is way more convenient)

thanks for the answer :)

[lukaseder]

Thank you very much for your suggestion. Yes indeed, we should do this for all of our secondary products and link to the notes from here: https://www.jooq.org/products