Examples: Updated the example of headers to utilize the App Router

[Sam-Phillemon9493]

This PR updates the headers example to use the App Router. Here are the changes that have been made:

• Renamed the "pages" folder to the "app" folder.
• Updated the routing for /, /about, and /news/[...slug] files to align with the App Router.
• Added the layout.tsx file as part of the App Router.
• Updated the package.json file.
• Updated the Readme file.

cc @samcx

[ijjk]

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[samcx]

@Sam-Phillemon9493 I'm not seeing the updates made to the package.json?

[Sam-Phillemon9493]

@Sam-Phillemon9493 I'm not seeing the updates made to the package.json?

@samcx Apologies! package.json was already up to date. I have removed that point from the comments above.

[samcx]

{
  "private": true,
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start"
  },
  "dependencies": {
    "next": "latest",
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  },
  "devDependencies": {
    "@types/node": "^18.11.5",
    "@types/react": "^18.0.23",
    "@types/react-dom": "^18.0.7",
    "typescript": "^4.8.4"
  }
}

@Sam-Phillemon9493 These are not the latest (e.g., react should be on 18.3.1, etc.)

[Sam-Phillemon9493]

{
  "private": true,
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start"
  },
  "dependencies": {
    "next": "latest",
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  },
  "devDependencies": {
    "@types/node": "^18.11.5",
    "@types/react": "^18.0.23",
    "@types/react-dom": "^18.0.7",
    "typescript": "^4.8.4"
  }
}

@Sam-Phillemon9493 These are not the latest (e.g., react should be on 18.3.1, etc.)

@samcx I've updated the react and react-dom to version 18.3.1 .

[samcx]

@Sam-Phillemon9493 Don't forget the devDependencies as well next time!