Add paragraph for root model behaviour

Author: markusjwetzel

README.md

@@ -49,34 +49,43 @@ Whenever a `Cat` or `Dog` model is instantiated, the attribute `type` will be se
 
 Other than that there is no magic and a `Cat` or a `Dog` model will behave just like a normal Eloquent model. You can define cat or dog specific attributes and relationships on these models. An attribute only set for dogs for example should be a nullable column on the table, so that it is set for dogs but `null` for other pets.
 
-### Custom type column
+### Root model behaviour
 
-By default the name of the type column is `type`. However, you can set a custom type column name:
+You can query the root model like any other model. However, the returned models will be transformed based by the type name. For example if there is one cat and one dog in the database, `Pet::all();` will return one `Dog` and one `Cat` model.
 
-```php
-use ProAI\Inheritance\Inheritance;
+It is not possible to use `new Pet($attributes);` when you specify the type in `$attributes`. Please use the static method `Pet::new($attributes)` instead. This method returns a new model based on the given type. For example if the type in `$attributes` is `App\Models\Cat`, it will return an instance of `App\Models\Cat`. If no type is specified, an instance of `App\Models\Pet` will be returned.
 
-class Pet extends Model
+### Custom type names
+
+If you want to use different names for the type column than the classname, you can use the static `$inheritanceMap` property:
+
+```php
+class Pet
 {
     use Inheritance;
 
-    protected static $inheritanceColumn = 'pet_type';
+    protected static $inheritanceMap = [
+        'cat' => Cat::class,
+        'dog' => Dog::class,
+    ];
 }
 ```
 
-### Custom type name
+### Custom type column
 
-If you want a different name than the classname, you can use the `$inheritanceType` property:
+By default the name of the type column is `type`. However, you can set a custom type column name:
 
 ```php
-class Cat extends Pet
+use ProAI\Inheritance\Inheritance;
+
+class Pet extends Model
 {
-    protected static $inheritanceType = 'cat';
+    use Inheritance;
+
+    protected static $inheritanceColumn = 'pet_type';
 }
 ```
 
-> Hint: The value of `$inheritanceType` can also be an enum value.
-
 ## Support
 
 Bugs and feature requests are tracked on [GitHub](https://github.com/proai/eloquent-inheritance/issues).