docs: update README with gotcha

README.md

@@ -59,12 +59,15 @@ Due to the large amount of records anticipated to be created, you must create an
 return [
 
     'morphs' => [
-        0 => App\Models\User::class
+        1 => App\Models\User::class
     ],
 
 ];
 ```
 
+> [!CAUTION]
+> `0` is not a valid key for the morph map, as it will get resolved to `false` in Laravel's morphing logic.
+
 This points our `App\Models\User::class` to an enum (integer). This means our database is created with small integers vs large fully qualified namespaces.
 
 Recommended action is creating an enum class to describe all models in your system. If an integer mapping is not detected. The system will error out with an `\InvalidArgumentException`.