Add webextensions.manifest.content scripts.world (#32084)

* Add webextensions.manifest.content_scripts.world

* Tweak

Author: rebloor

files/en-us/mozilla/add-ons/webextensions/api/scripting/executionworld/index.md

@@ -16,17 +16,17 @@ Values of this type are strings. Possible values are:
 
 - `ISOLATED`
 
-  The default execution environment of [content scripts](/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts).
+  The default [content scripts](/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts) execution environment.
   This environment is isolated from the page's context: while they share the same document, the global scopes and available APIs differ.
 
 - `MAIN`
 
-  The execution environment of the web page. This environment is shared with the web page, without isolation.
+  The web page execution environment. This environment is shared with the web page without isolation.
   Scripts in this environment do not have any access to APIs that are only available to content scripts.
 
-  > **Warning:** Due to the lack of isolation, the web page can detect the executed code and interfere with it.
+  > **Warning:** Due to the lack of isolation, the web page can detect and interfere with the executed code.
   > Do not use the `MAIN` world unless it is acceptable for web pages to read, access, or modify the logic or data that flows through the executed code.
-  > `MAIN` is not supported in Firefox (although it is planned and the work to introduce it is tracked by [Bug 1736575](https://bugzil.la/1736575)). In the meantime, JavaScript code running in the isolated content script sandbox can use the Firefox "Xray vision" feature, as described in [Share objects with page scripts](/en-US/docs/Mozilla/Add-ons/WebExtensions/Sharing_objects_with_page_scripts).
+  > `MAIN` is not supported in Firefox (although it is planned, and the work to introduce it is tracked by [Bug 1736575](https://bugzil.la/1736575)). In the meantime, JavaScript code running in the isolated content script sandbox can use the Firefox "Xray vision" feature, as described in [Share objects with page scripts](/en-US/docs/Mozilla/Add-ons/WebExtensions/Sharing_objects_with_page_scripts).
 
 ## Browser compatibility
 

files/en-us/mozilla/add-ons/webextensions/manifest.json/content_scripts/index.md

@@ -281,6 +281,38 @@ Details of all the keys you can include are given in the table below.
         </p>
       </td>
     </tr>
+    <tr>
+      <td>
+        <a id="run_at"><code>world</code></a>
+      </td>
+      <td><code>String</code></td>
+      <td>
+        <p>
+          The JavaScript world the script executes in.
+        </p>
+        <dl>
+          <dt><code>"ISOLATED"</code></dt>
+          <dd>
+            The default <a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts">content scripts</a> execution environment.
+            This environment is isolated from the page's context: while they share the same document, the global scopes and available APIs differ.
+          </dd>
+          <dt><code>"MAIN"</code></dt>
+          <dd>
+            The web page's execution environment.
+            This environment is shared with the web page without isolation.
+            Scripts in this environment don't have any access to the APIs that are only available to content scripts.
+            <div class="notecard warning" id="sect1">
+              <p>
+                <strong>Warning:</strong> Due to the lack of isolation, the web page can detect and interfere with the executed code.
+                Do not use the <code>MAIN</code> world unless it is acceptable for web pages to read, access, or modify the logic or data that flows through the executed code.
+                <code>worid</code>, and therefore <code>"MAIN"</code>, is not supported in Firefox (although it is planned, and the work to introduce it is tracked by <a href="https://bugzil.la/1736575" class="external" target="_blank">Bug 1736575</a>). In the meantime, JavaScript code running in the isolated content script sandbox can use the Firefox "Xray vision" feature, as described in <a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/Sharing_objects_with_page_scripts">Share objects with page scripts</a>.
+              </p>
+            </div>
+          </dd>
+        </dl>
+        <p>The default value is <code>"ISOLATED"</code>.</p>
+      </td>
+    </tr>
   </tbody>
 </table>