Add documentation for token discovery and swap API endpoints

[ckorhonen]

Summary

Adds developer documentation for the new token discovery and swap REST API endpoints introduced in os2-core#30466.

New documentation covers:

• GET /api/v2/tokens/top - Top tokens by 24h volume
• GET /api/v2/tokens/trending - Trending tokens
• GET /api/v2/chain/{chain}/token/{address} - Token details
• GET /api/v2/swap/quote - Swap quote with transaction data

Review & Testing Checklist for Human

• Verify response schemas match actual API - The example responses were inferred from the implementation code; test against the actual API to confirm field names and structure
• Verify parameter names - Confirm query parameter names (e.g., sell_token, buy_token, taker_address, sell_amount) match the actual API implementation
• Test example curl commands - Run the documented curl examples against staging/production to verify they work
• Verify ReadMe.com frontmatter - Confirm the category ID, slug, and parentDocSlug are correct for proper publishing

Recommended test plan:

1. Deploy os2-core#30466 to staging
2. Run the documented curl commands and compare responses to the examples
3. Trigger the rdme docs publish workflow and verify the new page appears correctly on docs.opensea.io

Notes

• Documentation was written based on the os2-core PR implementation; actual API testing was not performed
• Link to Devin run: https://app.devin.ai/sessions/e0c76d379a244b5cafb73fb5c22624ba
• Requested by: @ckorhonen

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[devin-ai-integration]

Original prompt from Chris K

Can you prepare updates to developer docs based on changes in this PR:
https://github.com/ProjectOpenSea/os2-core/pull/30466


You only need to look in the following repo: ProjectOpenSea/developer-docs

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[devin-ai-integration]

Devin Review found 1 potential issue.

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