Add WakaTime api for developer time tracking. (#874)

README.md

@@ -291,6 +291,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Restpack](https://restpack.io/) | Provides screenshot, HTML to PDF and content extraction APIs | `apiKey` | Yes | Unknown |
 | [Todoist](https://developer.todoist.com) | Todo Lists | `OAuth` | Yes | Unknown |
 | [Vector Express](http://vector.express) | Free vector file converting API | No | No | Yes |
+| [WakaTime](https://wakatime.com/developers) | Automated time tracking leaderboards for programmers | No | Yes | Unknown |
 | [Wunderlist](https://developer.wunderlist.com/documentation) | Todo Lists | `OAuth` | Yes | Unknown |
 
 ### Environment