[plugins.json] Add cocoapods-integrate-flutter

[Prateek Grover]

Please add the following entry to the plugins.json file:

{
  "gem": "cocoapods-integrate-flutter",
  "name": "CocoaPods Integrate Flutter",
  "author": "kerry",
  "url": "https://github.com/upgrad/cocoapods-integrate-flutter",
  "description": "A plugin to integrate flutter with existing iOS application."
}

[Orta Therox]

Cool, added with 82a15e0