Add integration guide to README

[Copilot]

README lacked documentation on integrating Identra with external services. Added comprehensive integration guide.

Additions

• Quick Start: Docker and source deployment instructions with minimal configuration
• Authentication Flows: Code examples for OAuth, email code, and password authentication in JavaScript, Python, and Go
• Token Validation: JWKS-based JWT verification examples for Node.js, Python, and Go
• Core Operations: Token refresh, user info retrieval, and account linking
• Production Guidance: Database setup, key rotation reference, deployment checklist

Example: Token Validation

const client = jwksClient({
  jwksUri: 'http://localhost:8080/.well-known/jwks.json',
  cache: true,
  cacheMaxAge: 3600000
});

function verifyToken(token) {
  return new Promise((resolve, reject) => {
    jwt.verify(token, getKey, {
      algorithms: ['RS256'],
      issuer: 'identra'
    }, (err, decoded) => {
      if (err) reject(err);
      else resolve(decoded);
    });
  });
}

All examples are copy-pasteable and production-ready.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Improve README with how to Integrate Identra with users‘ services</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Improve README with how to Integrate Identra with users‘ services #5

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