docs: Update ESM docs to clearify that it covers configuring ESM at runtime

Author: aklinker1

docs/guide/essentials/es-modules.md

@@ -1,12 +1,10 @@
 # ES Modules
 
-Currently, ESM entrypoints are opt-in, so you must configure each entrypoint with that in mind.
+You source code should always be written as ESM. However, you have some control whether an entrypoint is bundled as ESM.
 
 ## HTML Pages <Badge type="warning" text="≥0.0.1" />
 
-In general, you should always make HTML pages import ESM scripts, unless you need to support old browsers.
-
-To make a script ESM, add `type="module"`:
+Vite only supports bundling JS from HTML pages as ESM. Ensure you have added `type="module"` to your `<script>` tags:
 
 <!-- prettier-ignore -->
 ```html
@@ -33,6 +31,6 @@ Only MV3 supports ESM background scripts/service workers. When targeting MV2, th
 
 ## Content Scripts
 
-WXT does not yet include built-in support for ESM content scripts. The plan is to add support for chunking to reduce bundle size, but not support HMR for now. There are several technical issues that make implementing a generic solution for HMR impossible. See [Content Script ESM Support #357](https://github.com/wxt-dev/wxt/issues/357) for details.
+WXT does not yet include built-in support for bundling content scripts as ESM. The plan is to add support for chunking to reduce bundle size, but not support HMR for now. There are several technical issues that make implementing a generic solution for HMR impossible. See [Content Script ESM Support #357](https://github.com/wxt-dev/wxt/issues/357) for details.
 
-If you can't wait, and need ESM support right now, you can implement ESM support manually. See the [ESM Content Script UI](https://github.com/wxt-dev/examples/tree/main/examples/esm-content-script-ui) example to get started.
+If you can't wait, and need ESM support right now, you can implement ESM support manually. See the [ESM Content Script UI](https://github.com/wxt-dev/examples/tree/main/examples/esm-content-script-ui) example to learn how.