Update README.md: fixing 1 typo

[didier-durand]

Hi,

This PR fixes 1 typo on "inference" ( + dash for "on-device" as compound word)

I, didier-durand, confirm that I have read and understood the terms of the CLA of Kyutai-labs, as outlined in the repository's CONTRIBUTING.md of Kyutai-labs' Moshi, and I agree to be bound by these terms.

Best,

Didier

Checklist

• Read CONTRIBUTING.md, and accept the CLA by including the provided snippet. We will not accept PR without this.
• Run pre-commit hook.
• If you changed Rust code, run cargo check, cargo clippy, cargo test.

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