Update docs

Author: fredsted

docs/custom-actions/variables.md

@@ -70,6 +70,7 @@ These variables are automatically available for each request or email. Different
 | request.html_content              | Email         | Parsed HTML content                                                                                    |
 | request.destinations              | Email         | Comma separated list of recipients.                                                                    |
 | request.checks.[name]             | Email         | True or false for email checks (DKIM, SPF, etc.)                                                       |
+| error.[number]                    | All           | Created for all actions that result in an error, where `number` is the order of the action.            |
 
 ### Variable Modifiers
 

docs/news.markdown

@@ -24,6 +24,11 @@ Subscribe below to receive updates about improvements and new features on Webhoo
 </form>
 </div>
 
+## 22 September
+
+* Added `$error.[action]$` variable that is automatically created whenever an action result in an error.
+* Email notifications should now support dark mode in Apple Mail on iOS.
+
 ## 5 August 2025
 
 * Added Open In function to view requests in RapidAPI and Postman clients