Add Open Data DC (#873)

README.md

@@ -445,6 +445,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Data USA](https://datausa.io/about/api/) | US Public Data | No | Yes | Unknown |
 | [Data.gov](https://api.data.gov/) | US Government Data | `apiKey` | Yes | Unknown |
 | [Data.parliament.uk](http://www.data.parliament.uk/developers/) | Contains live datasets including information about petitions, bills, MP votes, attendence and more | No | No | Unknown |
+| [District of Columbia Open Data](http://opendata.dc.gov/pages/using-apis) | Contains D.C. government public datasets, including crime, GIS, financial data, and so on | No | Yes | Unknown |
 | [EPA](https://developer.epa.gov/category/apis/) | Web services and data sets from the US Environmental Protection Agency | No | Yes | Unknown |
 | [FEC](https://api.open.fec.gov/developers/) | Information on campaign donations in federal elections | `apiKey` | Yes | Unknown |
 | [Federal Register](https://www.federalregister.gov/reader-aids/developer-resources) | The Daily Journal of the United States Government | No | Yes | Unknown |