Upgrade syntax in the docs

[igrlk]

Hey everyone 👋

I found that graphql-js.org docs have old syntax (e.g. var, require whereas at least Enabling Stream & Defer section uses the modern syntax (const, import)
Getting Started page also says that the old syntax is used in the examples.

So wanted to ask:

• Can old syntax be replaced with modern one?
• Are there any important reasons why docs still have the old syntax?
  • Is it there so that a user can run the code without doing things like .mjs file extension & setting type: module in package.json to have imports or anything like that?

Looking forward to hearing back from you, thanks! 👍