Update README.md

Author: kochie

README.md

@@ -40,8 +40,9 @@ _(If you just want to use your Prism CSS-file themes, that's also no problem)_
 
 
 - [Installation](#installation)
-  - [Usage](#usage)
-  - [Custom Language Support](#custom-language-support)
+- [Usage](#usage)
+- [Custom Language Support](#custom-language-support)
+  - [Next.js](#Next.js)
 - [Basic Props](#basic-props)
   - [children](#children)
   - [language](#language)