[Added] instance call with config

[theo-sim-dev]

Fixes #252

What's Added

• A new section: "Calling the instance with a config object" (in English and other languages)
• Code example showing instance({ url, method }) usage
• Example retry pattern using error.config in an interceptor (commonly used in token refresh scenarios)

Why This Matters

While this behavior is supported and commonly used, it is not explicitly mentioned in the instance docs. Many developers discover it only through source code or trial-and-error. Documenting it helps with:

• Discoverability of advanced usage
• Retry logic based on error.config
• Cleaner, DRY error handling implementations

[jasonsaayman]

nicely done thanks