docs: add Parallel Search MCP example

[georgeatparallel]

Deep Code users can already extend the CLI through MCP, so the setup guides are a natural place to show a credential-free web search option. This adds the same copyable configuration to both language versions of the guide and leaves the built-in Web Search unchanged.

What changed

• Added Parallel Search MCP examples to the Chinese and English MCP guides.
• Used mcp-remote with Deep Code's existing stdio configuration path.

Validation

• Parsed both new JSON examples and verified their command, arguments, and endpoint.
• Checked bilingual parity, changed-file scope, and git diff --check.

Disclosure: I work at Parallel.ai, which operates this MCP endpoint.