chore: fix out-of-date code comment

packages/@lwc/engine-dom/src/custom-elements/create-custom-element.ts

@@ -10,17 +10,13 @@ import { createCustomElementUsingUpgradableConstructor } from './create-custom-e
 import type { LifecycleCallback } from '@lwc/engine-core';
 
 /**
- * We have three modes for creating custom elements:
+ * We have two modes for creating custom elements:
  *
  * 1. Compat (legacy) browser support (e.g. IE11). Totally custom, doesn't rely on native browser APIs.
  * 2. "Upgradable constructor" custom element. This allows us to have two LWC components with the same tag name,
  *    via a trick: every custom element constructor we define in the registry is basically the same. It's essentially
  *    a dummy `class extends HTMLElement` that accepts an `upgradeCallback` in its constructor ("upgradable
  *    constructor"), which allows us to have completely customized functionality for different components.
- * 3. "Scoped" (or "pivot") custom elements. This relies on a sophisticated system that emulates the "scoped custom
- *    elements registry" proposal, with support for avoiding conflicts in tag names both between LWC components and
- *    between LWC components and third-party elements. This uses a similar trick to #2, but is much more complex
- *    because it must patch the global `customElements` and `HTMLElement` objects.
  */
 export let createCustomElement: (
     tagName: string,