Add IconPacks.Avalonia to the README.md (#208)

Add IconPacks.Avalonia to the Theme & Icons section of the README.md

https://github.com/MahApps/IconPacks.Avalonia

README.md

@@ -204,6 +204,7 @@ Contributions are always welcome! Please take a look at the [Contribution Guidel
 - [HeroIcons.Avalonia](https://github.com/russkyc/heroicons-avalonia) - Hand crafted icons from [Heroicons](https://heroicons.com) made available to AvaloniaUI.
 - [Huskui.Avalonia](https://github.com/d3ara1n/Huskui.Avalonia) - A modern, elegant UI component library inspired by [ParkUI](https://park-ui.com/) and using the [Radix Colors](https://www.radix-ui.com/colors) palette.
 - [Icons.Avalonia](https://github.com/Projektanker/Icons.Avalonia) - A library to easily display icons in an Avalonia App.
+- [IconPacks.Avalonia](https://github.com/MahApps/IconPacks.Avalonia) Really awesome icon packs for Avalonia in one library. The IconPacks packages contains controls, markup extensions and converters to use these awesome icons with your Avalonia applications in a simple way.
 - [Lucide.Avalonia](https://github.com/dme-compunet/Lucide.Avalonia) - Implementation of the Lucide icon library for AvaloniaUI.
 - [LucideAvaloniaUI](https://github.com/MarwanFr/LucideAvaloniaUI) - A library for AvaloniaUI that integrates Lucide icons into your Avalonia applications.
 - [Magic.Icon](https://github.com/liwuqingxin/Magic.Icon) - An icon class generator for iconfont in avalonia and wpf.