Update stale documentation links to canonical URLs

[alewolf]

Summary

Several reference links in docs/REQUIREMENTS.md pointed at repos that have since been renamed or documentation domains that have migrated. None were hard 404s today — they all still resolve via redirects — but redirects for renamed GitHub repos can break if the old path is later reclaimed, and the migrated docs domains are the canonical homes now. This updates each to its current canonical URL.

Changes (docs/REQUIREMENTS.md)

Old	New	Reason
docs.anthropic.com/en/api/	platform.claude.com/docs/en/api/	Docs domain migration
docs.fal.ai/model-endpoints	fal.ai/docs/model-endpoints	Docs host consolidated
cloud.google.com/vertex-ai/docs/reference/rest	docs.cloud.google.com/vertex-ai/docs/reference/rest	Google docs domain change
platform.openai.com/docs/api-reference/	developers.openai.com/api/reference/overview	Docs site moved
docs.x.ai/docs/api-reference	docs.x.ai/developers/rest-api-reference/inference/chat	Old docs path
github.com/firebase/genkit	github.com/genkit-ai/genkit	Repo renamed
github.com/google/A2A	github.com/a2aproject/A2A	Repo moved (now under the Linux Foundation)

All seven replacement URLs were verified to return HTTP 200.

Props

Props @vyskoczilova for the contribution.

• https://github.com/vyskoczilova
• https://profiles.wordpress.org/vyskoczilova/

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Note

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Updates external documentation links in docs/REQUIREMENTS.md to reflect current vendor endpoints and repository locations.

Changes:

• Refreshes API documentation URLs (Anthropic, fal, Vertex AI, OpenAI, xAI).
• Updates GitHub repository links for Firebase Genkit and the A2A protocol.

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[felixarntz]

@alewolf Thank you for the PR!