Update free-programming-interactive-tutorials-en.md (#4715)

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-interactive-tutorials-en.md
Co-authored-by: NSeth <seth@elypia.org>
Co-authored-by: NSeth <seth@elypia.org>

free-programming-interactive-tutorials-en.md

@@ -280,6 +280,7 @@
 
 ### SQL
 
+* [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)
 * [SQLBolt](http://sqlbolt.com)