impl #796 observe media volume change (#798)

docs/recipes/optimize-storage.md

@@ -31,9 +31,11 @@ rrweb.record({
     // do not record mouse movement
     mousemove: false
     // do not record mouse interaction
-    mouseInteraction: false,
+    mouseInteraction: false
     // set the interval of scrolling event
     scroll: 150 // do not emit twice in 150ms
+    // set the interval of media interaction event
+    media: 800
     // set the timing of record input
     input: 'last' // When input mulitple characters, only record the final input
   }

docs/recipes/optimize-storage.zh_CN.md

@@ -34,6 +34,8 @@ rrweb.record({
     mouseInteraction: false,
     // 设置滚动事件的触发频率
     scroll: 150 // 每 150ms 最多触发一次
+    // set the interval of media interaction event
+    media: 800
     // 设置输入事件的录制时机
     input: 'last' // 连续输入时，只录制最终值
   }