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

Added zoom type to ZoomOptions
AgentME/DefinitelyTyped,mcliment/DefinitelyTyped,dsebastien/DefinitelyTyped,magny/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped,dsebastien/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,AgentME/DefinitelyTyped,magny/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped