add entity variants section

Author: NichtStudioCode

docs/nova.yml

@@ -72,6 +72,7 @@ nav:
             - "GUI Textures": "addon/fonts/guitextures.md"
             - "Action Bar Overlay": "addon/fonts/actionbar.md"
             - "Boss Bar Overlay": "addon/fonts/bossbar.md"
+      - "Entity Variants": "addon/entity-variants.md"
       - "Attachments": "addon/attachments.md"
       - "Abilities": "addon/abilities.md"
       - "Hitboxes": "addon/hitboxes.md"

docs/nova/addon/entity-variants.md

@@ -0,0 +1,29 @@
+## What is an Entity Variant?
+
+Entity variants are a vanilla Minecraft feature and allow you to add retextured variants of existing entities to the game. 
+([Minecraft Wiki](https://minecraft.wiki/w/Mob_variant))
+
+## Registering a custom entity variant
+You can register a custom entity variant like this:
+
+```kotlin
+@Init(stage = InitStage.PRE_PACK) // (1)!
+object EntityVariants  {
+    
+    val BLUE_COW by ExampleAddon.cowVariant("blue") {
+        spawnConditions { 
+            // (2)!
+        }
+        
+        texture(CowModelType.WARM /*(3)!*/) {
+            texture("entity/cow/blue")
+        }
+    }
+    
+}
+```
+
+1. Nova will load this class during addon initialization, causing your variants to be registered.
+2. The conditions for your custom variant to be selected when spawning. See [Minecraft Wiki - Spawn Conditions](https://minecraft.wiki/w/Mob_spawning#Spawn_conditions)
+ for more information.
+3. Some entities offer multiple model types. For example, the warm cow has horns. You can select the model type here.