doc: update file quickstart/client.mdx with correct NodeJS version

[samuel871211]

The code example use readline

......
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import readline from "readline/promises";
import dotenv from "dotenv";

Based on NodeJS official document

readline requires NodeJS 17 or above

Motivation and Context

Update document

How Has This Been Tested?

Update document only

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[dsp-ant]

Good catch, thank you