Update Prim.md (#127)

Author: saori-eth

docs/scripting/nodes/types/Prim.md

@@ -2,6 +2,8 @@
 
 Creates primitive 3D shapes with built-in geometry caching for optimal performance.
 
+Primitives origins are the in the middle of their shapes.
+
 ## Properties
 
 ### `.type`: String
@@ -273,4 +275,4 @@ app.add(triggerZone)
 - Physics bodies are centered to match the visual geometry
 - Dynamic bodies require the `mass` property to be set
 - Trigger volumes don't cause physical collisions but can detect overlaps
-- Physics callbacks (onContactStart, etc.) receive the other colliding object as a parameter
+- Physics callbacks (onContactStart, etc.) receive the other colliding object as a parameter