update readme

Author: zihejia

README.md

@@ -68,9 +68,9 @@ class _YourClassState extends State<YourClass> {
 ```
 Once you've called this method once, you can access `mixpanel` throughout the rest of your application.
 ### Tracking
-Once you've initialized the SDK, Mixpanel will <a href="https://mixpanel.com/help/questions/articles/which-common-mobile-events-can-mixpanel-collect-on-my-behalf-automatically" target="_blank">automatically collect common mobile events</a>. You can enable/ disable automatic collection through your <a href="https://mixpanel.com/help/questions/articles/how-do-i-enable-common-mobile-events-if-i-have-already-implemented-mixpanel" target="_blank">project settings</a>.
+Once you've initialized the SDK, Mixpanel will <a href="https://mixpanel.com/help/questions/articles/which-common-mobile-events-can-mixpanel-collect-on-my-behalf-automatically" target="_blank">automatically collect common mobile events</a>. You can enable/disable automatic collection through your project settings.
 With the `mixpanel` object created in [the last step](#integration) a call to `track` is all you need to send additional events to Mixpanel.
-```js
+```dart
 // Track with event-name
 mixpanel.track('Sent Message');
 // Track with event-name and property