Add a concise Quick Start section to improve first-time onboarding

[Nitya-003]

Description
The current README is very thorough and well-structured, especially for advanced and production use cases (streaming, retries, logging, custom fetch, proxies, etc.). However, for first-time users, the initial onboarding can feel overwhelming due to the amount of detailed information presented early on.

Adding a short Quick Start section at the top would significantly improve usability for new developers while keeping the rest of the documentation unchanged.

Proposed Improvement
Add a Quick Start section near the top of the README that includes:

• Minimal installation command
• Environment variable setup for GRADIENT_MODEL_ACCESS_KEY
• A short, end-to-end example showing:
  1. Client initialization
  2. A single chat.completions.create call
  3. Logging the response
     Example:

import Gradient from '@digitalocean/gradient';

const client = new Gradient({
  modelAccessKey: process.env.GRADIENT_MODEL_ACCESS_KEY,
});
const response = await client.chat.completions.create({
  model: 'llama3.3-70b-instruct',
  messages: [{ role: 'user', content: 'Hello!' }],
});
console.log(response.choices[0].message.content);

Why This Matters

• Reduces friction for new users trying the library for the first time
• Helps developers quickly validate their setup before diving into advanced features
• Aligns the README with common SDK documentation patterns used across the ecosystem

I’d be happy to open a PR implementing this Quick Start section if the maintainers agree with the approach.

hacktoberfest'25