clarify typeof alert behavior in non browser environment

[parthodas23]

The current page mentions:

typeof alert // "function"

But in Node.js / VS Code / terminal / online JS runners → alert does NOT exist. So it's gives undefined.

typeof alert // "undefined"

It should mention about the about the Browser Console

typeof alert // "function" (Browser Console)

[parthodas23]

I'd like to work on this issue and propose a small documentation update

I'll open a PR with suggested change about the Browser Console

typeof alert // "function" (Browser Console)