Update comment to say that background atlas can be null

Author: Swedz

src/main/java/aztech/modern_industrialization/inventory/BackgroundRenderedSlot.java

@@ -25,14 +25,16 @@
 
 import aztech.modern_industrialization.MI;
 import net.minecraft.resources.ResourceLocation;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Implement this on a slot to render its background automatically.
  */
 public interface BackgroundRenderedSlot {
     /**
-     * @return the {@link ResourceLocation} of the slot atlas texture to use for the slot background.
+     * @return the {@link ResourceLocation} of the slot atlas texture to use for the slot background. Return null to render no background.
      */
+    @Nullable
     default ResourceLocation getBackgroundAtlasLocation() {
         return MI.id("textures/gui/container/slot_atlas.png");
     }