update stock footage

content/snippets/stock-footage.en.md

@@ -15,9 +15,11 @@ Here is a list of free resources for pictures/music/videos/etc i use:
 
 * https://allthefreestock.com
 * <https://archive.org/search.php?query=licenseurl:http*publicdomain*>
-* https://www.wikimedia.org
+* https://commons.wikimedia.org
 * https://mzlw.de/materialien/
 * https://shotcut.org/resources/
+* https://search.creativecommons.org
+* http://eng.letscc.net/cc_intro.php
 
 # Pictures
 
@@ -30,9 +32,11 @@ Here is a list of free resources for pictures/music/videos/etc i use:
 * https://undraw.co/illustrations
 * https://thispersondoesnotexist.com
 * https://pix-zip.herokuapp.com
-* https://search.creativecommons.org
+* https://www.flickr.com/creativecommons
+* https://piqs.de/
 
 # Clipart
+
 * https://openclipart.org
 * https://publicdomainvectors.org
 
@@ -56,10 +60,20 @@ Here is a list of free resources for pictures/music/videos/etc i use:
 * https://freepd.com
 * https://cchound.com
 * https://www.jamendo.com/
+* https://starfrosch.ch
+
+* http://free-loops.com/
+* https://rappers.in/
+* https://free-beats.net/
+* https://www.looperman.com/
 
 # Sound
 
 * https://freesound.org/
+* https://audiyou.de
+* https://soundbible.com/
+* https://www.pacdv.com/sounds/
+* https://www.salamisound.de/
 
 # Game Assets
 
@@ -73,6 +87,10 @@ Here is a list of free resources for pictures/music/videos/etc i use:
 * [Openshot Luma transitions](https://github.com/OpenShot/openshot-qt/tree/master/src/transitions/extra)
 * [Kdenlive Luma transitions](https://github.com/KDE/kdenlive/tree/master/data/lumas/HD)
 
+# School / Education
+
+* http://www.cc-your-edu.de/
+* https://www.oercommons.org/
 
 ***