Docs: some installation commands should be dev dependencies instead of normal dependencies

Created by: gejimayu

When going through the docs, i saw many installation commands that are supposed to be dev dependencies.

For example: https://create-react-app.dev/docs/adding-typescript

npm install --save typescript @types/node @types/react @types/react-dom @types/jest

# or

yarn add typescript @types/node @types/react @types/react-dom @types/jest

I believe some dependencies such as typescript should be dev dependencies so that it's not included in the production bundle.