ASP.NET Core El Kitabı (#2891)

* ASP.NET Core El Kitabı

ASP.NET Core El Kitabı

* fix spacing, heading

copied the heading from another list; the link didn't work.
The linter enforces spacing between sections

* one more space

free-programming-books-tr.md

@@ -15,6 +15,7 @@
 * [LaTeX](#latex)
 * [Linux](#linux)
 * [Matlab](#matlab)
+* [.NET Framework](#net-framework)
 * [PHP](#php)
 * [Python](#python)
   * [Django](#django)
@@ -105,6 +106,11 @@
 * [Matlab Programlamaya Giris](http://ismailari.com/blog/matlab-programlamaya-giris/)
 
 
+### .NET Framework
+
+* [ASP.NET Core El Kitabı](https://sahin.gitbook.io/asp-net-core-el-kitab)
+
+
 ### PHP
 
 * [PHP - Laravel 4 Türkçe Dokumantasyon](https://leanpub.com/laravel4-tr)