update comments

Author: Chris Yang

shell/platform/darwin/ios/framework/Source/vsync_waiter_ios.h

@@ -18,6 +18,8 @@
 // Whether the max refresh rate on iPhone Pro-motion devices are enabled.
 // This reflects the value of `CADisableMinimumFrameDurationOnPhone` in the
 // info.plist file.
+//
+// Note on iPads that support Pro-motion, the max refresh rate is always enabled.
 @property(class, nonatomic, readonly) BOOL maxRefreshRateEnabledOnIPhone;
 
 //------------------------------------------------------------------------------