Update 3.0.4.md

Author: ralfhandl

versions/3.0.4.md

@@ -2017,8 +2017,8 @@ The key value used to identify the Path Item Object is an expression, evaluated
 
 ##### Patterned Fields
 
-| Field Pattern                                 |                Type                 | Description                                                                                                                                             |
-| --------------------------------------------- | :---------------------------------: | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| Field Pattern                                  |                 Type                  | Description                                                                                                                                                                     |
+| ---------------------------------------------- | :-----------------------------------: | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | <a name="callback-expression"></a>{expression} | [Path Item Object](#path-item-object) | A Path Item Object used to define a callback request and expected responses. A [complete example](https://learn.openapis.org/examples/v3.0/callback-example.html) is available. |
 
 This object MAY be extended with [Specification Extensions](#specification-extensions).