update docs

docs/recipes/canvas.md

@@ -0,0 +1,23 @@
+# Canvas
+
+Canvas is a special HTML element, which will not be recorded by rrweb by default. There are some options for recording and replaying Canvas.
+
+Enable recording Canvas：
+
+```js
+rrweb.record({
+  emit(event) {},
+  recordCanvas: true,
+});
+```
+
+Enable replaying Canvas：
+
+```js
+const replayer = new rrweb.Replayer(events, {
+  UNSAFE_replayCanvas: true,
+});
+replayer.play();
+```
+
+**Enable replaying Canvas will remove the sandbox, which may cause a potential security issue.**