Add lazy-load property to TabContent

docs/README.md

@@ -141,6 +141,13 @@ props: {
     type: String,
     default: ''
   },
+  /***
+   * Only render the content when the tab is active
+   */
+  lazy: {
+    type: Boolean,
+    default: false
+  },
   /***
    * Function to execute before tab switch. Return value must be boolean
    * If the return result is false, tab switch is restricted