mcptoon: replace the unpublished @modelcontextprotocol/server-fetch example

[activeing123]

The mcptoon page's first example installs a package that no longer exists on npm:

mcptoon add [fetch] --stdio npx -y [@modelcontextprotocol/server-fetch]

Checked against the registry today:

• registry.npmjs.org/@modelcontextprotocol%2Fserver-fetch → 404 (unpublished)
• registry.npmjs.org/@modelcontextprotocol%2Fserver-everything → 200 (published)

So anyone copying that line gets an npm error 404 before they ever reach the tool. This patch points both examples at the package that actually exists, keeping the file's existing bracket-placeholder style:

mcptoon add [everything] --stdio npx -y [@modelcontextprotocol/server-everything]
mcptoon call [everything] [echo] '{"message":"hi"}' --toon

Full disclosure: I maintain mcptoon, so I have an interest in the page being accurate — but the two commands above are simply the ones documented in the project README, which is what the page should mirror. The <!-- verified: --> stamp and everything else in the file are untouched.