Add comment to object declaration in README

[Chamber6821]

This PR prevents recurring misunderstanding: #298 objectionary/eo#3327

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PR-Codex overview

This PR introduces a new object in EO, demonstrating basic output functionality.

Detailed summary

• Added a new object titled "My first object in EO!" to README.md.
• Defined an argument args that takes input hello.
• Used QQ.io.stdout to output the string "Hello, world!\n".

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[yegor256]

@Chamber6821 thanks!