Add OpenAPI spec configuration options

[moutonjeremy]

Introduce configuration options for OpenAPI spec title, description, and version, allowing users to customize the generated API documentation. Default values are provided, and tests ensure correct functionality of these features.

[Copilot]

Pull request overview

This PR adds user-configurable OpenAPI info metadata (title, description, version) to the Fiber OpenAPI wrapper so generated specs (and auto-served /openapi.json) can reflect application-specific branding/versioning.

Changes:

• Extend Config with OpenAPITitle, OpenAPIDescription, and OpenAPIVersion, including defaults and merge logic.
• Use the new config fields when generating the OpenAPI info block.
• Update README and example app usage; add tests covering defaults, overrides, partial overrides, and auto-served spec behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
types.go	Adds new Config fields for OpenAPI info metadata.
fiberoapi.go	Provides defaults, merges new config fields, and injects them into the generated OpenAPI spec.
config_test.go	Adds tests validating default/custom/partial OpenAPI info behavior and the auto-served JSON route.
README.md	Documents new defaults and shows how to override the OpenAPI info block.
_examples/simple/main.go	Demonstrates the new info configuration options in an example.

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