Renamed doc to docs and minor language fixes

docs/examples/with_widgets_overlay/lib/example_game.dart

@@ -0,0 +1,38 @@
+import 'package:flame/game.dart';
+import 'package:flame/gestures.dart';
+import 'package:flame/palette.dart';
+
+import 'package:flutter/material.dart';
+
+class ExampleGame extends Game with HasWidgetsOverlay, TapDetector {
+  bool isPaused = false;
+
+  @override
+  void update(double dt) {}
+
+  @override
+  void render(Canvas canvas) {
+    canvas.drawRect(const Rect.fromLTWH(100, 100, 100, 100),
+        Paint()..color = BasicPalette.white.color);
+  }
+
+  @override
+  void onTap() {
+    if (isPaused) {
+      removeWidgetOverlay('PauseMenu');
+      isPaused = false;
+    } else {
+      addWidgetOverlay(
+          'PauseMenu',
+          Center(
+            child: Container(
+              width: 100,
+              height: 100,
+              color: const Color(0xFFFF0000),
+              child: const Center(child: const Text('Paused')),
+            ),
+          ));
+      isPaused = true;
+    }
+  }
+}