Fix iframe syntax in overview.md

Author: ewowi

docs/develop/overview.md

@@ -8,4 +8,4 @@
 * [Layers](https://moonmodules.org/MoonLight/develop/layers/): Coordinate system Effects and Modifiers run in.
 * [Sveltekit](https://moonmodules.org/MoonLight/develop/sveltekit/): Explaining the repository MoonLight is forked from
 
-<iframe width="560" height="315" src="https://www.youtube.com/embed/tdrU9yGkyVo"/>
+<iframe width="560" height="315" src="https://www.youtube.com/embed/tdrU9yGkyVo" frameborder="0" allowfullscreen/>