Add Plino API

Plino is a free, intelligent spam filtering system that doesn't need an API key to function. This commit adds Plino to the list of Spam filters, just below OOPSpam

README.md

@@ -442,6 +442,7 @@ API | Description | Auth | HTTPS | CORS |
 | [OneSignal](https://documentation.onesignal.com/docs/onesignal-api) | Self-serve customer engagement solution for Push Notifications, Email, SMS & In-App | `apiKey` | Yes | Unknown |
 | [OOPSpam](https://oopspam.com/) | Multiple spam filtering service | No | Yes | Yes |
 | [PageCDN](https://pagecdn.com/docs/public-api) | Public API for javascript, css and font libraries on PageCDN | `apiKey` | Yes | Yes |
+| [Plino](https://plino.herokuapp.com/) | An intelligent spam filtering system | No | Yes | No |
 | [Postman](https://docs.api.getpostman.com/) | Tool for testing APIs | `apiKey` | Yes | Unknown |
 | [ProxyCrawl](https://proxycrawl.com) | Scraping and crawling anticaptcha service | `apiKey` | Yes | Unknown |
 | [Public APIs](https://github.com/davemachado/public-api) | A collective list of free JSON APIs for use in web development | No | Yes | Unknown |