Documentation: Update library READMEs with current API

[joshrotenberg]

Overview

The redis-cloud and redis-enterprise library READMEs have outdated examples that don't match the current API.

Issues Found

1. redis-cloud/README.md:

   • Shows old API methods like list_subscriptions instead of handler pattern
   • Missing examples of using handlers
   • Config structure doesn't match current implementation

2. redis-enterprise/README.md:

   • Shows old API methods like get_cluster_info instead of handler pattern
   • Missing builder pattern examples
   • Doesn't show current client initialization

Tasks

• Update redis-cloud README with current API examples
• Update redis-enterprise README with current API examples
• Add more comprehensive usage examples
• Document all available handlers
• Add authentication configuration examples
• Add error handling examples
• Update version numbers to match crates.io

Current API Pattern

// Cloud
let client = CloudClient::new("api_key", "api_secret")?;
let subscriptions = client.subscription().list().await?;

// Enterprise  
let client = EnterpriseClient::builder()
    .url("https://cluster:9443")
    .username("admin")
    .password("password")
    .insecure(true)
    .build()?;
let cluster = client.cluster().get().await?;