Add docs for layout property

docs/examples/styles/layout.py

@@ -0,0 +1,52 @@
+from textual import layout
+from textual.app import App
+from textual.widget import Widget
+from textual.widgets import Static
+
+
+class LayoutApp(App):
+    CSS = """
+    #vertical-layout {
+        layout: vertical;
+        background: $panel;
+        height: auto;
+    }
+    #horizontal-layout {
+        layout: horizontal;
+        background: $panel-darken-1;
+        height: auto;
+    }
+    #center-layout {
+        layout: center;
+        background: $panel-darken-2;
+        height: 7;
+    }
+    Screen Static {
+        margin: 1;
+        width: 12;
+        color: $text-primary;
+        background: $primary;
+    }
+    """
+
+    def compose(self):
+        yield layout.Container(
+            Static("Layout"),
+            Static("Is"),
+            Static("Vertical"),
+            id="vertical-layout",
+        )
+        yield layout.Container(
+            Static("Layout"),
+            Static("Is"),
+            Static("Horizontal"),
+            id="horizontal-layout",
+        )
+        yield layout.Container(
+            Static("Center"),
+            id="center-layout",
+        )
+
+
+app = LayoutApp()
+app.run()