Standardize OpenAPI spec references to .yaml across docs

[fern-api]

Summary

Standardizes OpenAPI specification file references from .yml to .yaml across documentation pages for consistency with the project structure page and starter template.

Problem

User feedback reported that the quickstart page mentions openapi.yaml in the starter template file tree but then uses .yml in the fern init command, causing confusion when following along. The same inconsistency appeared across several other pages.

Changes

• quickstart.mdx: fern init --openapi /path/to/openapi.yml → .yaml
• generate-api-ref.mdx: Config example and file trees updated from openapi.yml → openapi.yaml
• generate-webhook-ref.mdx: Config example and file trees updated from openapi.yml → openapi.yaml
• commands.mdx: CLI reference example updated from openapi.yml → openapi.yaml
• snippets/openapi-specs.mdx: Shared snippet updated from openapi.yml → openapi.yaml

Fern config files (docs.yml, generators.yml) remain .yml — this change only affects OpenAPI spec file references.

Requested by: Fern Support

[fern-api]

Requested by: devin
Slack thread: View conversation

[github-actions]

🌿 Preview your docs: https://fern-preview-fern-clarify-yaml-yml-quickstart.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/api-definitions/openapi/extensions/api-version
• learn/api-definitions/openapi/extensions/method-names
• learn/cli-generator/get-started/openapi-extensions
• learn/docs/getting-started/project-structure
• learn/docs/getting-started/quickstart
• learn/sdks/deep-dives/customize-method-names