[plugins.json] Add cocoapods-ug

[Coder-Miao]

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

{
  "gem": "cocoapods-ug",
  "name": "CocoaPods Ug",
  "author": "Teemo",
  "url": "https://github.com/Naaaac/cocoapods-ug.git",
  "description": "A longer description of cocoapods-ug."
}