Added Perspective API

Perspective is a free API that uses machine learning to identify "toxic" comments, making it easier to host better conversations online.

README.md

@@ -760,6 +760,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Keen IO](https://keen.io/) | Data Analytics | `apiKey` | Yes | Unknown |
 | [NLP Cloud](https://nlpcloud.io) | NLP API using spaCy and transformers for NER, sentiments, classification, summarization, and more | `apiKey` | Yes | Unknown |
 | [OpenVisionAPI](https://openvisionapi.com) | Open source computer vision API based on open source models | No | Yes | Yes |
+| [Perspective](https://perspectiveapi.com) | NLP API to return probability that if text is toxic, obscene, insulting or threatening | Yes | Yes | Unknown |
 | [Time Door](https://timedoor.io) | A time series analysis API | `apiKey` | Yes | Yes |
 | [Unplugg](https://unplu.gg/test_api.html) | Forecasting API for timeseries data | `apiKey` | Yes | Unknown |
 | [Wit.ai](https://wit.ai/) | Natural Language Processing | `OAuth` | Yes | Unknown |