Update free-courses-de.md (#11679)

* Update free-courses-de.md

Added a new HTML course

* Update courses/free-courses-de.md

---------

Co-authored-by: Eric Hellman <eric@hellman.net>

courses/free-courses-de.md

@@ -47,6 +47,7 @@
 
 * [CSS lernen](https://youtube.com/playlist?list=PLuBK_vNnGp8ANspdZh_aRAa1InIhFlgm_) - NEW - Vadim
 * [HTML Tutorial Deutsch](https://youtube.com/playlist?list=PLnlqg5o1zhnhVI3t1iTE2oO4QSGpu7EMx) - Markus Reichl
+* [HTML Tutorial Deutsch](https://youtube.com/playlist?list=PL_pqkvxZ6ho3Dho4bGSJfEXn38fI9VuC7) - Programmieren Starten
 
 
 #### Bootstrap