Add SQL Teaching (#5806)

* Interactive: Add SQL Teaching

* Update  alphabetical ordering

more/free-programming-interactive-tutorials-en.md

@@ -342,6 +342,7 @@
 * [Intro to SQL: Querying and managing data](https://www.khanacademy.org/computing/computer-programming/sql) - Khan Academy
 * [SQL at Codecademy](https://www.codecademy.com/courses/learn-sql)
 * [SQL Server Tutorial](https://www.tutlane.com/tutorial/sql-server) - tutlane
+* [SQL Teaching](https://www.sqlteaching.com)
 * [SQL Tutorial](https://www.w3schools.com/sql) - W3Schools
 * [SQLBolt](http://sqlbolt.com)