add sentry profiling header for document response (#789)

Author: nichtsam

app/entry.server.tsx

@@ -36,6 +36,10 @@ export default async function handleRequest(...args: DocRequestArgs) {
 	responseHeaders.set('fly-primary-instance', primaryInstance)
 	responseHeaders.set('fly-instance', currentInstance)
 
+	if (process.env.NODE_ENV === 'production' && process.env.SENTRY_DSN) {
+		responseHeaders.append('Document-Policy', 'js-profiling')
+	}
+
 	const callbackName = isbot(request.headers.get('user-agent'))
 		? 'onAllReady'
 		: 'onShellReady'