[meta] Release preparation steps for 10.2.0

@longwave and I agreed that we would like to get ✨ Add "json" as core data type Active in before beta (allow it in between alpha and beta) if it's ready before beta, so adding it to the issue summary's target issues list.

What is the drop-dead date for the JSON data types issue to be included?

10.2.0-beta1 is due next week → and feature and API additions have to land there → in order to make it into 10.2.0.

OK thanks... Seems very tight to get it from where it is to RTBC by then, but we'll see how far I can get it in the next few days.

Added the docs critical for attribute plugin discovery.

Adding a critical regression.

Another critical.

Adding missing PhpRequirements child.

Automatically closed - issue fixed for 2 weeks with no activity.

This was for 10.2.0