docs: enhance UI libraries guide with official ShadCN integration link (#1825)

## 🎯 Changes

Add link to the ShadCN library guide for integrating TanStack Form.

## ✅ Checklist

- [x] I have followed the steps in the [Contributing guide](https://github.com/TanStack/form/blob/main/CONTRIBUTING.md).
- [x] I have tested this code locally with `pnpm test:pr`.

## 🚀 Release Impact

- [ ] This change affects published code, and I have generated a [changeset](https://github.com/changesets/changesets/blob/main/docs/adding-a-changeset.md).
- [x] This change is docs/CI/dev-only (no release).

Author: kostyniuk

docs/framework/react/guides/ui-libraries.md

@@ -156,3 +156,5 @@ The process for integrating shadcn/ui components is similar. Here's an example u
 - The integration approach is the same as with Mantine and Material UI.
 - The primary difference lies in the specific shadcn/ui component properties and styling options.
 - Note the onCheckedChange property of Checkbox instead of onChange.
+
+The ShadCN library includes a dedicated guide covering common scenarios for integrating TanStack Form with its components: https://ui.shadcn.com/docs/forms/tanstack-form