chore(docs): mark v0 API as "deprecated" and v1 as "stable"

[rvagg]

Ref: #13249

@rjan90 @TippyFlitsUK any idea of what might break if we rename these files in documentation/en?

[Copilot]

Pull Request Overview

This PR updates the Lotus API documentation and code to clarify API versioning by marking the v0 API as "deprecated", the v1 API as "stable", and the v2 API as "experimental". The changes primarily involve renaming output files to reflect these stability levels and updating comments throughout the codebase.

• Refactors documentation generation to use descriptive file names indicating API stability
• Updates API interface documentation to clarify version stability and recommendations
• Reorganizes code structure with constants for better maintainability

Reviewed Changes

Copilot reviewed 7 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
gen/docs/main.go	Refactored to use constants for file paths with stability indicators and reorganized generation functions
documentation/en/api-methods-v2-experimental.md	Updated experimental API warning message for clarity
api/v2api/full.go	Enhanced documentation to clarify experimental status and recommend v1 API
api/v0api/gateway.go	Updated comments to mark v0 as deprecated and v1 as stable
api/v0api/full.go	Added deprecation warning and recommendation to use v1 API
api/api_gateway.go	Added comprehensive documentation for Gateway API purpose and stability
api/api_full.go	Updated comments to indicate v1 API stability

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[rjan90]

I do not think there anything will break, at least from the https://lotus.filecoin.io perspective.