docs: add head `<script>` example (#2264)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

docs/reference/site-config.md

@@ -94,6 +94,7 @@ export default {
   title: 'My Awesome Site'
 }
 ```
+
 ```md
 # Hello
 ```
@@ -113,6 +114,7 @@ export default {
   titleTemplate: 'Custom Suffix'
 }
 ```
+
 ```md
 # Hello
 ```
@@ -159,8 +161,29 @@ export default {
     [
       'link',
       { rel: 'preconnect', href: 'https://fonts.gstatic.com', crossorigin: '' }
+      // would render:
+      //
+      // <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
+    ],
+
+    [
+      'script',
+      { id: 'register-sw' },
+      `;(() => {
+        if ('serviceWorker' in navigator) {
+          navigator.serviceWorker.register('/sw.js')
+        }
+      })()`
+      // would render:
+      //
+      // <script id="register-sw">
+      // ;(() => {
+      //   if ('serviceWorker' in navigator) {
+      //     navigator.serviceWorker.register('/sw.js')
+      //   }
+      // })()
+      // </script>
     ]
-    // would render: <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
   ]
 }
 ```
@@ -295,7 +318,7 @@ export default {
 }
 ```
 
-It can also be an array of extact url string, regex patterns, or custom filter functions. 
+It can also be an array of exact url string, regex patterns, or custom filter functions.
 
 ```ts
 export default {