Should mention differentiation between property schema changes and item data changes

The constructor with a propertychanged mentions that it should only be used for object schema changes and with adequate `ListChangedType` value.

This is in contrast to item changes, which specify item indices and different `ListChangedType` values.

The remarks section on this type, `ListChangedEventArgs`, should mention and describe this differentiation.

Furthermore, it is unclear how a combination of the two should be handled. The `ListChangedType` can not be combined, but constructors with both types of parameters imply this is somehow possible and intended, but they do not document how it's supposed to work/be handled.

---
#### Document Details

⚠ *Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.*

* ID: 97c8c9f6-72f6-2fb9-feed-d9a0bfb6348f
* Version Independent ID: 72c6439d-375b-e584-fd70-593411554e41
* Content: [ListChangedEventArgs Class (System.ComponentModel)](https://docs.microsoft.com/en-us/dotnet/api/system.componentmodel.listchangedeventargs?view=netframework-4.7.2)
* Content Source: [xml/System.ComponentModel/ListChangedEventArgs.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.ComponentModel/ListChangedEventArgs.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**

Start with xml/System.ComponentModel/ListChangedEventArgs.xml and its constructors and remarks, then review the referenced ListChangedType documentation to establish the distinction between property-schema and item-data changes. Done means the remarks clearly explain both cases and how constructor arguments should be handled together.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.