Add ITIS API (#1075)

README.md

@@ -696,6 +696,7 @@ API | Description | Auth | HTTPS | CORS |
 | [GBIF](http://api.gbif.org/v1/) | Global Biodiversity Information Facility | No | Yes | Yes |
 | [iDigBio](https://github.com/idigbio/idigbio-search-api/wiki) | Access millions of museum specimens from organizations around the world | No | Yes | Unknown |
 | [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 |
 | [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 |