Fix one of the typing, add a missing jsdoc.
Fix one of the typing, add a missing jsdoc.

magny/DefinitelyTyped,magny/DefinitelyTyped,dsebastien/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped