Update index.d.ts
Update index.d.ts

Correct the wrong word
AgentME/DefinitelyTyped,magny/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,borisyankov/DefinitelyTyped,dsebastien/DefinitelyTyped,AgentME/DefinitelyTyped,markogresak/DefinitelyTyped,AgentME/DefinitelyTyped