docs: add custom link example for mantine (#3033)

docs/framework/react/guide/custom-link.md

@@ -159,3 +159,30 @@ export const CustomLink: LinkComponent<typeof MUILinkComponent> = (props) => {
   return <CreatedLinkComponent preload={'intent'} {...props} />
 }
 ```
+
+### Mantine example
+
+```tsx
+import * as React from "react";
+import { createLink, LinkComponent } from "@tanstack/react-router";
+import { Anchor, AnchorProps } from "@mantine/core";
+
+interface MantineAnchorProps extends Omit<AnchorProps, "href"> {
+  // Add any additional props you want to pass to the anchor
+}
+
+const MantineLinkComponent = React.forwardRef<
+  HTMLAnchorElement,
+  MantineAnchorProps
+>((props, ref) => {
+  return <Anchor ref={ref} {...props} />;
+});
+
+const CreatedLinkComponent = createLink(MantineLinkComponent);
+
+export const CustomLink: LinkComponent<typeof MantineLinkComponent> = (
+  props
+) => {
+  return <CreatedLinkComponent preload="intent" {...props} />;
+};
+```