docs: fix typo in Mantine package name (#2051)

Author: myabc

docs/content/docs/getting-started/mantine.mdx

@@ -9,17 +9,17 @@ imageTitle: Mantine rich text editor using BlockNote
 [Mantine](https://mantine.dev/) is an open-source collection of React components.
 
 ```console tab="npm"
-npm install @mantine/core @mantine/hooks @mantine/util
+npm install @mantine/core @mantine/hooks @mantine/utils
 npm install @blocknote/core @blocknote/react @blocknote/mantine
 ```
 
 ```console tab="pnpm"
-pnpm add @mantine/core @mantine/hooks @mantine/util
+pnpm add @mantine/core @mantine/hooks @mantine/utils
 pnpm add @blocknote/core @blocknote/react @blocknote/mantine
 ```
 
 ```console tab="bun"
-bun add @mantine/core @mantine/hooks @mantine/util
+bun add @mantine/core @mantine/hooks @mantine/utils
 bun add @blocknote/core @blocknote/react @blocknote/mantine
 ```