office-js: Clarify description of ItemChanged (#30387)
office-js: Clarify description of ItemChanged (#30387)

* office-js: Clarify description of ItemChanged

* update based on feedback

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