Document filter property and improve audiences documentation

[devin-ai-integration]

Summary

Improves documentation for the filter property and audiences property in the generators.yml reference. This addresses feedback that these filtering mechanisms were not adequately documented.

Changes:

• Added a ParamField for settings.filter explaining it's used to limit which endpoints are included in the generated SDK
• Enhanced the settings.filter.endpoints description to clarify the expected format (METHOD /path) and behavior (only listed endpoints are included, all others excluded)
• Expanded the audiences property description to explain how it filters API elements based on audience tags, and linked to the comprehensive guide

Updates since last revision

• Added cross-references between audiences and filter so users understand both filtering options
• Clarified that audiences works for both SDKs and docs (not just SDKs)
• Added link to the docs audiences guide in addition to the SDK guide
• Added links from the SDKs audiences guide to the OpenAPI audiences and Fern Definition audiences pages for detailed syntax
• Added Tip boxes on both the SDKs audiences page and OpenAPI audiences page mentioning filter as an alternative for path-based filtering

Review & Testing Checklist for Human

• Verify anchor links work correctly: #openapi, #audiences, #settingsfilter in generators-yml-reference
• Verify all guide links work:
  • /learn/sdks/deep-dives/audiences
  • /learn/docs/api-references/audiences
  • /learn/api-definitions/openapi/extensions/audiences
  • /learn/api-definitions/ferndef/audiences
• Check the preview deployment to ensure both filter and audiences documentation render correctly
• Verify the Tip boxes appear correctly on both audiences pages (SDKs and OpenAPI)

Notes

Requested by Fern Support based on Slack thread where Josh Studt noted that filter was not documented in the generators.yml reference. Follow-up questions about audiences documentation and the relationship between the two filtering mechanisms led to the additional improvements.

Link to Devin run: https://app.devin.ai/sessions/2576905507da480ba340d749ead72d7a

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-041c4903-a053-4575-9940-403558f9085f.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/api-definitions/openapi/extensions/audiences
• learn/sdks/deep-dives/audiences
• learn/sdks/reference/generators-yml

[github-actions]

📝 [vale] _{reported by reviewdog 🐶}
[FernStyles.Adverbs] Remove 'naturally' if it's not important to the meaning of the statement.