Add SQL and SQL Server trainings (#11238)

* Add a databases section with SQL and SQL Server training.

* Fix the errors in the pull request: Correct blank line formatting and remove the empty "Databases" section

* Fix: Use a single SQL category.

courses/free-courses-tr.md

@@ -9,6 +9,7 @@
 * [JavaScript](#javascript)
 * [Python](#python)
 * [React](#react)
+* [SQL](#sql)
 * [Temel programlama](#temel-programlama)
 * [Version Control Systems](#version-control-systems)
 
@@ -81,6 +82,12 @@
 * [Yeni Başlayanlar İçin React](https://www.youtube.com/playlist?list=PL-Hkw4CrSVq_eyixSZ4sVI1x6d7akLpsy) - Arin Yazilim
 
 
+### SQL
+
+* [Her Yönüyle SQL Server](https://www.btkakademi.gov.tr/portal/course/her-yonuyle-sql-server-9007) - Ömer Faruk Çolakoğlu
+* [Uygulamalarla SQL Öğreniyorum](https://www.btkakademi.gov.tr/portal/course/uygulamalarla-sql-ogreniyorum-8249) - Ömer Faruk Çolakoğlu
+
+
 ### Temel programlama
 
 * [Bilgisayar programlama I](https://acikders.ankara.edu.tr/course/view.php?id=8750) - Semra Gündüç