Fix typo in README.md

[alexravenna]

fix typo

Description

Checklist

• Formatted with cargo fmt
• Built with nix build
• Ran flake checks with nix flake check
• Added or updated relevant tests (leave unchecked if not applicable)
• [ x ] Added or updated relevant documentation (leave unchecked if not applicable)
• Linked to related issues (leave unchecked if not applicable)

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[cole-h]

Thanks for your contribution! This was actually a duplicate of #817, which I pulled into #854.