typo in readme

[EllaGogo]

UPDATE: So I found out that you can also use YES, closing the issue

Hey,
not a big deal but in your readme is written :

Opt-in to the embedded views preview by adding a boolean property to the app's Info.plist file with the key io.flutter.embedded_views_preview and the value YES.

obviously, the value should be true. If you want to make it even more easy for users, I recommend to change the text above to:

Opt-in to the embedded views preview by adding these lines to the app's Info.plist file:
<key>io.flutter.embedded_views_preview</key> <true/>