[plugins.json] Add cocoapods-mexdup

[ashine]

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

{
  "gem": "cocoapods-mexdup",
  "name": "CocoaPods Mexdup",
  "author": "ashine",
  "url": "https://github.com/JHshine/cocoapods-mexdup",
  "description": "A longer description of cocoapods-mexdup."
}

[ashine]

rm