chore(examples): update with-mantine (vercel#34591)

[Mantine ](https://mantine.dev/) is a fully featured React components
library.
This PR adds an example of Mantine + Next.js

## Documentation / Examples

- [x] Make sure the linting passes by running `yarn lint`

Co-authored-by: Balázs Orbán <info@balazsorban.com>

examples/with-mantine/README.md

@@ -1,14 +1,20 @@
-# TypeScript & Mantine Next.js example
+# Example app with mantine
 
-This is a simple project that shows the usage of Next.js with TypeScript and Mantine.
+This example features how you use [mantine](https://github.com/mantine/mantine), a React component library.
+
+## Preview
+
+Preview the example live on [StackBlitz](http://stackblitz.com/):
+
+[![Open in StackBlitz](https://developer.stackblitz.com/img/open_in_stackblitz.svg)](https://stackblitz.com/github/vercel/next.js/tree/canary/examples/with-mantine)
 
 ## Deploy your own
 
-Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example) or preview live with [StackBlitz](https://stackblitz.com/github/vercel/next.js/tree/canary/examples/with-typescript-mantine)
+Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example) or preview live with [StackBlitz](https://stackblitz.com/github/vercel/next.js/tree/canary/examples/with-mantine)
 
-[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/git/external?repository-url=https://github.com/vercel/next.js/tree/canary/examples/with-typescript-mantine&project-name=with-typescript-mantine&repository-name=with-typescript-mantine)
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/git/external?repository-url=https://github.com/vercel/next.js/tree/canary/examples/with-mantine&project-name=with-mantine&repository-name=with-mantine)
 
-## How to use it?
+## How to use
 
 Execute [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app) with [npm](https://docs.npmjs.com/cli/init), [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/), or [pnpm](https://pnpm.io) to bootstrap the example: