Add Avalonia to the .NET Open Source Developer Projects A cross-platform UI framework that supports XAML and .NET (#1384)

Co-authored-by: Maira Wenzel <[email protected]>

Author: Apollo9999

dotnet-developer-projects.md

@@ -15,6 +15,7 @@ Please sort projects alphabetically and provide a one-line description. GitHub/C
 
 ## Platforms
   * [Akka.NET](http://github.com/akkadotnet) - Akka.NET is a toolkit and runtime for building highly concurrent, distributed, and fault tolerant event-driven applications on .NET & Mono. This community-driven port brings C# & F# developers the capabilities of the original Akka framework in Java/Scala. [[Project Site]](http://getakka.net/)
+  * [Avalonia](https://github.com/AvaloniaUI/Avalonia) - A cross-platform UI framework that supports XAML and .NET for building desktop applications.  
   * [Castle Project](https://github.com/castleproject) - Umbrella project for ActiveRecord, DynamicProxy, MonoRail, Windsor
   * [Catel](https://github.com/catel/catel) - Application platform with IoC, logging, reflection and much more that serves as a base for applications that must be ready for future growth.
   * [Enterprise Web Library (EWL)](https://github.com/enduracode/enterprise-web-library) - An extremely opinionated platform for web applications that trades off performance, scalability, and development flexibility for an ease of maintenance you won't find anywhere else. [Enterprise Web Library site](http://www.enterpriseweblibrary.org/).

dotnet-free-oss-services.md

@@ -35,6 +35,7 @@ Please sort projects alphabetically and provide a one-line description. Where po
 * [Coverity Scan](https://scan.coverity.com) - Static analysis service to identify defects in C# code.
 * [dotCover](https://www.jetbrains.com/buy/opensource/?product=dotCover) - Code coverage tool integrated with Visual Studio.
 * [.Net Reflector](http://reflectorblog.red-gate.com/2013/07/open-source) - Browse, analyse and decompile IL code.
+* [Sonarqube](https://www.sonarsource.com/open-source-editions/)-static code analysis tools out there. It is an open-source platform for continuous inspection of code quality and performs automatic reviews via static code analysis
 
 ## Package Management
 
@@ -43,8 +44,11 @@ Please sort projects alphabetically and provide a one-line description. Where po
 ## Analytics and Error Reporting
 
 * [Bugsnag](https://bugsnag.com/blog/bugsnag-loves-open-source) - Cross platform error reporting.
-* [elmah.io](https://elmah.io/sponsorship/opensource/) - Error logging and uptime monitoring for .NET.
-* [Sentry](https://sentry.io/for/open-source/) - Cross platform error reporting.
+* [countly](https://countly.com) - comprehensive product analytics platform needed to build outstanding and innovative products and the most privacy-conscious solution for mobile, 
+   desktop, and web applications for all users.
+* [elmah](https://elmah.io) - Error logging and uptime monitoring for .NET.
+* [Sentry](https://sentry.io/welcome/) - Cross platform error reporting.
+
 
 ## Cloud Resources and Services