Improve API docs

[lucassus]

This pull request focuses on improving documentation for the API client and its controllers by enhancing clarity and consistency. Key changes include updating import statements in examples, refactoring method signatures for better readability, and standardizing the formatting of type references in the documentation.

Documentation Enhancements:

• Import Statements in Examples:

  • Added import { Client, Environment } from '@maxio-com/advanced-billing-sdk'; to initialization examples in README.md and doc/client.md for improved clarity. [1] [2]

• Standardized Type References:

  • Updated type references in response descriptions across multiple files to use backticks (e.g., [Invoice] → [`Invoice`]) for consistent formatting. This change affects methods in doc/controllers/advance-invoice.md, doc/controllers/api-exports.md, doc/controllers/billing-portal.md, and doc/controllers/component-price-points.md. [1] [2] [3] [4] and others)

Code Example Improvements:

• Refactored Method Signatures:
  • Refactored method signatures in doc/controllers/api-exports.md and doc/controllers/component-price-points.md to use destructured parameter objects for better readability and scalability. [1] [2] [3] [4]