Added Aster reference

Author: JKorf

README.md

@@ -73,6 +73,7 @@ CryptoExchange.Net also allows for [easy access to different exchange API's](htt
 
 |Exchange|Repository|Nuget|
 |--|--|--|
+|Aster|[JKorf/Aster.Net](https://github.com/JKorf/Aster.Net)|[![Nuget version](https://img.shields.io/nuget/v/JKorf.Aster.net.svg?style=flat-square)](https://www.nuget.org/packages/JKorf.Aster.Net)|
 |Binance|[JKorf/Binance.Net](https://github.com/JKorf/Binance.Net)|[![Nuget version](https://img.shields.io/nuget/v/Binance.net.svg?style=flat-square)](https://www.nuget.org/packages/Binance.Net)|
 |BingX|[JKorf/BingX.Net](https://github.com/JKorf/BingX.Net)|[![Nuget version](https://img.shields.io/nuget/v/JK.BingX.net.svg?style=flat-square)](https://www.nuget.org/packages/JK.BingX.Net)|
 |Bitfinex|[JKorf/Bitfinex.Net](https://github.com/JKorf/Bitfinex.Net)|[![Nuget version](https://img.shields.io/nuget/v/Bitfinex.net.svg?style=flat-square)](https://www.nuget.org/packages/Bitfinex.Net)|