docs: correct content script example code (#1811)

Author: howlettt

CONTRIBUTING.md

@@ -182,5 +182,5 @@ Anyone is welcome to submit a blog post on <https://wxt.dev/blog>!
 > [!NOTE]
 > Before starting on a blog post, please message Aaron on Discord or start a discussion on GitHub to get permission to write about a topic, but most topics are welcome: Major version updates, tutorials, etc.
 
-- **English only**: Blog posts should be written in English. Unfortunately, our maintainers doesn't have the bandwidth right now to translate our docs, let alone blog posts. Sorry 😓
+- **English only**: Blog posts should be written in English. Unfortunately, our maintainers don't have the bandwidth right now to translate our docs, let alone blog posts. Sorry 😓
 - **AI**: Please only use AI to translate or proof-read your blog post. Don't generate the whole thing... We don't want to publish that.

docs/guide/essentials/entrypoints.md

@@ -300,14 +300,14 @@ When defining content script entrypoints, keep in mind that WXT will import this
 
 <!-- prettier-ignore -->
 ```ts
-browser.runtime.onMessage.addListener((message) => { // [!code --]
-  // ... // [!code --]
-}); // [!code --]
+const container = document.createElement('div'); // [!code --]
+document.body.append(container); // [!code --]
 
-export default defineBackground(() => {
-  browser.runtime.onMessage.addListener((message) => { // [!code ++]
-    // ... // [!code ++]
-  }); // [!code ++]
+export default defineContentScript({
+  main: function () {
+    const container = document.createElement('div'); // [!code ++]
+    document.body.append(container); // [!code ++]
+  },
 });
 ```