Update document.d.ts (#29465)
Update document.d.ts (#29465)

Document.getInitialProps() is awaitable.
georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,borisyankov/DefinitelyTyped,AgentME/DefinitelyTyped,magny/DefinitelyTyped,dsebastien/DefinitelyTyped,AgentME/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,AgentME/DefinitelyTyped,AgentME/DefinitelyTyped,dsebastien/DefinitelyTyped