Add AppFocus and AppBlur to the events

Now that they're supported by more than just textual-web it makes sense to
expose them a little better in the docs.

docs/events/app_blur.md

@@ -0,0 +1,20 @@
+# AppBlur
+
+The `AppBlur` event is sent to the application when the terminal window
+loses focus.
+
+!!! note
+    Only available when running under textual-web or within terminals that
+    support `FocusIn` reporting.
+
+## Attributes
+
+_No other attributes_
+
+## Code
+
+::: textual.events.AppBlur
+
+## See also
+
+- [AppFocus](app_focus.md)

docs/events/app_focus.md

@@ -0,0 +1,20 @@
+# AppFocus
+
+The `AppFocus` event is sent to the application when the terminal window
+gains focus.
+
+!!! note
+    Only available when running under textual-web or within terminals that
+    support `FocusOut` reporting.
+
+## Attributes
+
+_No other attributes_
+
+## Code
+
+::: textual.events.AppFocus
+
+## See also
+
+- [AppBlur](app_blur.md)

mkdocs-nav.yml

@@ -43,6 +43,8 @@ nav:
           - "css_types/vertical.md"
       - Events:
           - "events/index.md"
+          - "events/app_blur.md"
+          - "events/app_focus.md"
           - "events/blur.md"
           - "events/click.md"
           - "events/descendant_blur.md"