Add AdditionalTestEnchantment section.

Register-Enchantments.md

@@ -3,17 +3,17 @@ Registering your enchantment allow Custom Anvil to use your enchantment.
 To register your enchantment, you need into a `CAEnchantment` instance and then register it. \
 This is so Custom Anvil know how to handle action with your enchantment like adding/removing and getting level of it from an item.
 
-## Create the Custom Anvil enchantment
+# Creating a Custom Anvil enchantment
 
-### If you were able to register your enchantment to the bukkit registry. 
+## If you were able to register your enchantment to the bukkit registry. 
 Then you should use or extend `CABukkitEnchantment`
 
 ```java
 CAEnchantment enchantment = new CABukkitEnchantment(bukkitEnchant);
 ```
 
-### If your enchantment is not registered into the bukkit registry 
-For example if you store via persistent data: 
+## If your enchantment is not registered into the bukkit registry 
+For example, if you store via persistent data: 
 
 Then you should preferably create a class extending `CAEnchantmentBase` and implement the required functions:
 * `getLevel`: To get the enchantment level using item and item meta.
@@ -33,7 +33,12 @@ You also need 3 objects for the constructor:
 <br></br>
 You can also directly implement `CAEnchantment`, but it is not recommended.
 
-## Registering your custom anvil enchantment
+## Custom Restriction
+You may want to implement AdditionalTestEnchantment to your Custom Anvil Enchantment class. It allows you to add external restriction:
+* `isEnchantConflict`: Test if the enchantment is compatible with a provided enchantment map. (key = enchantment, value = level)
+* `isItemConflict`: Test if this enchantment is compatible with a provided item (and its enchantments) 
+
+# Registering your custom anvil enchantment
 ```java
 EnchantmentApi.registerEnchantment(enchantment);
 ```