Fix arg help string to match 'classes' arg name.

[NauchtanRobotics]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Correction of the --classes argument help text in detect.py.

📊 Key Changes

• Fixed a typo in the command-line argument help text for --classes.

🎯 Purpose & Impact

• Clarifies how to use the --classes argument, improving the user experience.
• Ensures accurate documentation, preventing potential confusion among developers and users when filtering detections by class.

[github-actions]

👋 Hello @NauchtanRobotics, thank you for submitting a 🚀 PR! To allow your work to be integrated as seamlessly as possible, we advise you to:

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[glenn-jocher]

@NauchtanRobotics PR is merged. Thank you for your contributions to YOLOv5 🚀 and Vision AI ⭐