The things in parentheses ((Release note), (NEWS)) should probably be links

This line is duplicate

"RubyVM::InstructionSequence#to_binary" should be marked up with ` ` to highlight it, similar to the items on line 25. There are other spots on this page where you're using module names, functions, commands, etc. without markup as well, so please go through the whole doc and mark them up.

I'm not sure if this is a mistake or not; is this list item supposed to be under "Promote stdlib to default gems"? It seems like it should be on the same level and its children should be one level up (** instead of ***), but I could be wrong.

Pro tip: If you add a line above each example that says [source,*language*], you'll get syntax highlighting in the rendered page. In this example it's [source,json], in the subsequent examples it's [source,ruby].

Looks good other than the couple of notes above.

Thank you, merged.