docs: fix formats attribute name (#1441)

Author: ahmed-bhs

core/content-negotiation.md

@@ -97,7 +97,7 @@ api_platform:
 Support for specific formats can also be configured at resource and operation level using the `input_formats` and `output_formats` attributes.
 `input_formats` controls the formats accepted in request bodies while `output_formats` controls formats available for responses.
 
-The `format` attribute can be used as a shortcut, it sets both the `input_formats` and `output_formats` in one time.
+The `formats` attribute can be used as a shortcut, it sets both the `input_formats` and `output_formats` in one time.
 
 ```php
 <?php