Fix example in README.md for 1.21

[TrashyDaFox]

I tried using the client example in the README.md file, but it is broken in 1.21, I fixed it by adding filtered_message with an empty string to the part where it sends a text packet

[extremeheat]

Can you update the example also?

[TrashyDaFox]

what do you mean? i already did

[extremeheat]

There are client examples in the example folder

[extremeheat]

Thanks