doc: fix Google Drive example (#3855)

Refs: c1407070fbb30eb4fb04cb6cb9f64be28f87fab7

packages/@uppy/companion/README.md

@@ -36,7 +36,7 @@ app.use(session({ secret: 'some secrety secret' }))
 // be sure to place this anywhere after app.use(bodyParser.json()) and app.use(session({...})
 const options = {
   providerOptions: {
-    google: {
+    drive: {
       key: 'GOOGLE_KEY',
       secret: 'GOOGLE_SECRET',
     },