docs: update content

docs/src/docPages/api/extensions.md

@@ -56,18 +56,3 @@ const editor = new Editor({
 
 Learn [more about custom extensions in our guide](/guide/extend-extensions).
 
-### ProseMirror plugins
-ProseMirror has a fantastic eco system with many amazing plugins. If you want to use one of them, you can register them with tiptap like that:
-
-```js
-import { history } from 'prosemirror-history'
-
-const History = Extension.create({
-  addProseMirrorPlugins() {
-    return [
-      history(),
-      // …
-    ]
-  },
-})
-```