Draft changelog: MCP servers for X API and docs

[mintlify]

Summary

Adds a Jun 30, 2026 changelog entry covering the two new hosted MCP servers shipped this week.

Changes

• New Jun 30, 2026 entry describing X MCP (api.x.com/mcp) and Docs MCP (docs.x.com/mcp).
• Highlights capabilities (Posts, Search, Users, Bookmarks, News & Trends, Articles) and the xurl mcp OAuth bridge.
• Links to the MCP guide and its subsections for client setup.

Context

Source PR introduced tools/mcp.mdx, which documents both servers — this is the user‑facing shipment for the week.

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