Level Editor: new page containing tutorials

Add some more up-to-date resources on the Level Editor to the wiki.

Reference: <https://forum.freegamedev.net/viewtopic.php?f=69&t=7811>
Suggested-by: darkhog

Level-Editor.md

@@ -0,0 +1,10 @@
+## Editor Tutorials
+
+There are various videos on the internet documenting the use of the built-in level editor. This is a list of some of the useful ones. However, due to the nature of the internet this list is probably incomplete. You're always welcome to add new ones!
+
+- [Basic Tutorial](https://www.youtube.com/watch?v=gsuKAy18iWo) by brmbrmcar
+- [Basic Tutorial (Part 1/2)](https://www.youtube.com/watch?v=mhSNateb4nI) by Oliver Buo
+- [Basic Tutorial (Part 2/2)](https://www.youtube.com/watch?v=NLWhteLNcC8) by Oliver Buo
+- [Advanced Tutorial (Part 1/2)](https://www.youtube.com/watch?v=WBdwwcLD-vw) by Oliver Buo
+- [Advanced Tutorial (Part 2/2)](https://www.youtube.com/watch?v=UoaGDuBax6E) by Oliver Buo
+- [Expert Tutorial](https://www.youtube.com/watch?v=lL3oZbPfw08) by Oliver Buo