Add Smithery to tool documentation (vercel#6297)

## Background
Adding Smithery to the docs as an additional toolkit.

## Verification
Only the documentation was changed. No tests required.

Co-authored-by: Nico Albanese <49612682+nicoalbanese@users.noreply.github.com>

Author: calclavia

content/docs/02-foundations/04-tools.mdx

@@ -94,6 +94,7 @@ There are several providers that offer pre-built tools as **toolkits** that you
 - **[agentic](https://github.com/transitive-bullshit/agentic)** - A collection of 20+ tools. Most tools connect to access external APIs such as [Exa](https://exa.ai/) or [E2B](https://e2b.dev/).
 - **[browserbase](https://docs.browserbase.com/integrations/vercel-ai/introduction)** - Browser tool that runs a headless browser
 - **[browserless](https://docs.browserless.io/ai-integrations/vercel-ai-sdk)** - Browser automation service with AI integration - self hosted or cloud based
+- **[Smithery](https://smithery.ai/docs/use/connect)** - Smithery provides an open marketplace of 6K+ MCPs, including [Browserbase](https://browserbase.com/) and [Exa](https://exa.ai/).
 - **[Stripe agent tools](https://docs.stripe.com/agents)** - Tools for interacting with Stripe.
 - **[StackOne ToolSet](https://docs.stackone.com/agents)** - Agentic integrations for hundreds of [enterprise SaaS](https://www.stackone.com/integrations)
 - **[Toolhouse](https://docs.toolhouse.ai/toolhouse/using-vercel-ai)** - AI function-calling in 3 lines of code for over 25 different actions.