README example vs typescript

[cdncat]

Hello! Thanks for creating this library :)
Just wanted to note that display="initial" is part of the example in the README but in node_modules/react-iframe/types.d.ts, typescript will complain that the display attribute can only have "block" | "none" | "inline".

[robbestad]

Thanks for pointing this out. Added it to the types and also changed it the README to block