Added docs for the new compose method

docs/examples/guide/layout/utility_containers_using_with.py

@@ -0,0 +1,21 @@
+from textual.app import App, ComposeResult
+from textual.containers import Horizontal, Vertical
+from textual.widgets import Static
+
+
+class UtilityContainersExample(App):
+    CSS_PATH = "utility_containers.css"
+
+    def compose(self) -> ComposeResult:
+        with Horizontal():
+            with Vertical(classes="column"):
+                yield Static("One")
+                yield Static("Two")
+            with Vertical(classes="column"):
+                yield Static("Three")
+                yield Static("Four")
+
+
+if __name__ == "__main__":
+    app = UtilityContainersExample()
+    app.run()