[plugins.json] Add cocoapods-gitee

[Cong-Cong Pan]

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

{
  "gem": "cocoapods-gitee",
  "name": "CocoaPods Gitee",
  "author": "SyMind",
  "url": "https://gitee.com/SyMind/cocoapods-gitee",
  "description": "Using gitee mirrors to download dependencies."
}

[Cong-Cong Pan]

@orta please.