Update README.md

Author: CodingOctocat

README.md

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-# WpfObservableRangeCollection
+# WpfObservableRangeCollection
+
+Provides ObservableRangeCollection and its WPF version, including AddRange, RemoveRange, Replace/ReplaceRange methods for bulk operation, but only update the notification once.
+
+---
+## Classes
+- `ObservableRangeCollection`: Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.
+  > Forked from [XamarinCommunityToolkit/src/CommunityToolkit/Xamarin.CommunityToolkit/ObjectModel/ObservableRangeCollection.shared.cs](https://github.com/xamarin/XamarinCommunityToolkit/blob/main/src/CommunityToolkit/Xamarin.CommunityToolkit/ObjectModel/ObservableRangeCollection.shared.cs)
+
+- `WpfObservableRangeCollection`: Wpf version of ObservableRangeCollection with CollectionView support.
+  > Forked from [weitzhandler/wpfobservablerangecollection-cs](https://gist.github.com/weitzhandler/65ac9113e31d12e697cb58cd92601091#file-wpfobservablerangecollection-cs)
+
+## Why WpfObservableRangeCollection?
+See [ObservableCollection Doesn't support AddRange method, so I get notified for each item added, besides what about INotifyCollectionChanging? - StackOverflow](https://stackoverflow.com/q/670577/4380178)
+
+I've searched the web for some ObservableCollections that have *Range methods, but they all raise various exceptions(and some strange problems) in certain specific situations:
+- System.NotSupportedException: Range actions are not supported.
+- System.InvalidOperationException: The "2" index in the collection change event is not valid for collections of size "1".
+- More? I'm not sure. I forgot.
+
+In the end, I chose `XamarinCommunityToolkit/ObservableRangeCollection` and `weitzhandler/WpfObservableRangeCollection` and made slight changes to the code, and finally, I didn't encounter any problems, for now.
+
+## Seealso
+- [weitzhandler/RangeObservableCollection.cs - Gist](https://gist.github.com/weitzhandler/65ac9113e31d12e697cb58cd92601091)
+  - [My comment](https://gist.github.com/weitzhandler/65ac9113e31d12e697cb58cd92601091?permalink_comment_id=4634920#gistcomment-4634920)