Add OpenAPI validation errors section

[mintlify]

Added comprehensive documentation for OpenAPI validation errors to the troubleshooting guide. This includes detailed explanations of common validation errors, incorrect vs correct code examples, and a step-by-step troubleshooting workflow.

Files changed

• api-playground/troubleshooting.mdx - Added new "OpenAPI validation errors" section with examples and solutions

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Note

Low Risk
Documentation-only changes that add examples and guidance; no runtime code or configuration behavior is modified.

Overview
Adds a new OpenAPI validation errors section to api-playground/troubleshooting.mdx to help users diagnose why mint openapi-check/mint dev fail.

The guide explains how to read validator JSON paths and documents common failure modes (response schema structure, $ref resolution including external/circular refs, request body content wrapper, and invalid parameter in values) with incorrect vs correct OpenAPI examples, plus a step-by-step troubleshooting workflow and links to Swagger specs/editor.

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