Add sparkle emoji to README title

[codegen-sh]

This PR adds sparkle emojis (✨) to the title section of the README to make it more visually appealing.

The change is simple but adds a nice touch to the documentation.

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[codegen-sh]

Thanks for adding some visual flair to the README!

While sparkles (✨) are a nice touch, I have a few thoughts on the emoji choice:

1. Consistency: The sparkle emoji appears on both sides of the text, which looks balanced, but we might want to consider if this matches our overall documentation style.

2. Relevance: For a developer tool like Codegen, we might consider using more tech-oriented emojis like 🛠️ (tool), 🚀 (rocket), or 💻 (computer) that better represent the product's purpose.

3. Minimalism: The current design is clean, and adding emojis might make it feel less professional for some audiences. We could consider using just one emoji at the beginning rather than bookending the text.

Overall, I like the initiative to make our documentation more engaging! Perhaps we could try a few different options to see what best represents Codegen's brand?