updated webpack 4.0 optimization options comments for linter
updated webpack 4.0 optimization options comments for linter

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