[plugins.json] Add cocoapods-githooks

[caoyanbin]

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

{
  "gem": "cocoapods-githooks",
  "name": "CocoaPods Githooks",
  "author": "andy805.cao",
  "url": "https://github.com/EXAMPLE/cocoapods-githooks",
  "description": "A longer description of cocoapods-githooks."
}