Add MPDS: the public source of the materials science data

README.md

@@ -678,6 +678,7 @@ API | Description | Auth | HTTPS | CORS |
 | [inspirehep.net](https://inspirehep.net/info/hep/api?ln=en) | High Energy Physics info. system | No | Yes | Unknown |
 | [ITIS](https://www.itis.gov/ws_description.html) | Integrated Taxonomic Information System | No | Yes | Unknown |
 | [Launch Library](https://launchlibrary.net/docs/1.3/api.html) | Upcoming Space Launches | No | Yes | Unknown |
+| [Materials Platform for Data Science](https://mpds.io) | Curated experimental data for materials science | `apiKey` | Yes | No |
 | [Minor Planet Center](http://www.asterank.com/mpc) | Asterank.com Information | No | No | Unknown |
 | [NASA](https://api.nasa.gov) | NASA data, including imagery | No | Yes | Unknown |
 | [NASA APOD (unofficial API)](https://apodapi.herokuapp.com/) | API for getting APOD (Astronomy Image of the Day) images along with metadata | No | Yes | Yes |