Fix duplicate Highlights anchor in 0.86 release post

The pre-truncate teaser "### Highlights" and the "## Highlights"
section heading both slug to "highlights", so Docusaurus generated two
table-of-contents entries (#highlights and #highlights-1).

Drop the redundant "## Highlights" section wrapper and promote its three
subsections to top-level headings, matching the structure of the 0.84
release post. The sidebar now shows a single Highlights entry followed by
the highlight topics.

Author: fabriziocucci

website/blog/2026-06-11-react-native-0.86.mdx

@@ -21,15 +21,13 @@ Following 0.83, this is the second React Native release with no user-facing brea
 
 {/* truncate */}
 
-## Highlights
-
-### A New Home for React Native
+## A New Home for React Native
 
 The React Native repository, together with React, Metro, Yoga and the React Native Website, has moved from the `facebook` GitHub organization to the `react` organization. This move reflects the transition of React and React Native to the [React Foundation](https://react.foundation/), an independent foundation dedicated to the long-term stewardship of the React ecosystem.
 
 GitHub will automatically redirect all existing URLs, issues and PRs to the new location, so no action is required on your part.
 
-### Edge-to-Edge on Android
+## Edge-to-Edge on Android
 
 React Native 0.86 ships comprehensive fixes for Android 15+ edge-to-edge mode, including when it's enforced by the OS but not explicitly enabled via the `edgeToEdgeEnabled` Gradle property.
 
@@ -41,7 +39,7 @@ Key fixes include:
 - **`StatusBar`** now supports updating status bar style and visibility while a Modal is open.
 - **Navigation bar** contrast respects the theme's `enforceNavigationBarContrast` attribute.
 
-### React Native DevTools Improvements
+## React Native DevTools Improvements
 
 React Native DevTools now supports **light/dark mode emulation** via `Emulation.setEmulatedMedia`, allowing you to test your app's appearance mode handling directly from DevTools without changing your device settings. Use `cmd`/`ctrl` + `shift` + `P` to access from the Command Palette.