Include instructions for connecting to server in Tasks example

Discussed in https://github.com/google/comprehensive-rust/discussions/1316

Originally posted by njr0 October 6, 2023 .. I made it run OK (by just adding tokio = { version = "1.32.0", features = ["full"] } as a dependency in Cargo.toml, and I could get it to say connection from 127.0.0.1:64382 etc. by using curl, but I guess I'd have to write code to connect to the socket and receive the question and send a reply and stuff. Presumably, that's what's in the "prepared main.rs. ..

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nc or telnet are good tools for this. It's not HTTPS, so curl's not a good choice.

This should be mentioned in the speaker notes.