Update mcp-servers-for-cloudflare.mdx

[Kiki-Y123]

Adds documentation clarifying that Client IP Address Filtering on Cloudflare API tokens is incompatible with Cloudflare's MCP servers. Background:

• Cloudflare MCP servers run as Workers
• API requests originate from Worker subrequest IPs, not user eyeball IPs
• IP allowlists cause MCP authentication to fail
• Worker IPs are not stable/guaranteed, so allowlisting them is not recommended This update helps users avoid authentication issues when creating API tokens for MCP usage. Related internal issue: CUSTESC-63123

Summary

Screenshots (optional)

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