add self to contributor header

d3/d3.d.ts

@@ -1,6 +1,6 @@
 // Type definitions for d3JS
 // Project: http://d3js.org/
-// Definitions by: Boris Yankov <https://github.com/borisyankov>
+// Definitions by: Alex Ford <https://github.com/gustavderdrache>, Boris Yankov <https://github.com/borisyankov>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
 declare module d3 {