Update Cloudflare Workers Nodejs guide

[theWorkFsz]

Based on the new Cloudflare Workers project template and the official explanation of .dev.var, like

https://developers.cloudflare.com/workers/configuration/secrets/

https://github.com/cloudflare/workers-sdk/issues/5756#issuecomment-2094930088

update the relevant paragraphs in the guide regarding the definition of Env type.

[KnorpelSenf]

Gonna get back to this soon, sorry for the delay

[KnorpelSenf]

Oof it's been almost 2 months, that's much slower than what I wanted it to be ………

[KnorpelSenf]

Oof it's been almost 2 months, that's much slower than what I wanted it to be ………

[rojvv]

Closing due to inactivity.

[KnorpelSenf]

@theWorkFsz feel free to reopen if you want to pick this up again