Add jsdocs + remove unnessecary union return type
Add jsdocs + remove unnessecary union return type

rolandzwaga/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,AgentME/DefinitelyTyped,markogresak/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,AgentME/DefinitelyTyped,one-pieces/DefinitelyTyped,dsebastien/DefinitelyTyped,rolandzwaga/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,mcliment/DefinitelyTyped,magny/DefinitelyTyped