Add sequence diagram

Author: allcaps

README.md

@@ -3,6 +3,23 @@
 **Wagtail Translate** adds machine translations to your Wagtail site, with built-in support for [DeepL](https://www.deepl.com) and the flexibility to integrate other translation services.
 It automatically detects when a page is copied to a new locale and initiates the translation process.
 
+```mermaid
+sequenceDiagram
+    actor User
+    box Your web-application
+    participant Wagtail
+    participant Wagtail Translate
+    end
+    participant Translation Service
+
+    User->>Wagtail: Translate page
+    Wagtail->>Wagtail Translate: Fire 'copy for translation done' signal
+    Wagtail Translate->>Translation Service: Request translation
+    Translation Service->>Wagtail Translate: Return translated text
+    Wagtail Translate->>Wagtail: Save revision
+    User->>Wagtail: Publish page
+```
+
 [Wagtail Localize](https://wagtail-localize.org/) and [Wagtail Simple Translation](https://docs.wagtail.org/en/stable/reference/contrib/simple_translation.html) are the go-to solutions for multi-language Wagtail projects.
 Wagtail Localize offers advanced features that may be excessive for many projects, while Wagtail Simple Translation only copies pages to new locales, requiring manual translation.