docs: remove out of dated note

assertJSONFragment() no longer uses assertArraySubset()
See 88b7ba5

Author: kenjis

user_guide_src/source/testing/feature.rst

@@ -381,9 +381,6 @@ Asserts that $fragment is found within the JSON response. It does not need to ma
     // Is true
     $result->assertJSONFragment(['config' => ['key-a']]);
 
-.. note:: This simply uses PHPUnit's own `assertArraySubset() <https://phpunit.readthedocs.io/en/7.2/assertions.html#assertarraysubset>`_
-    method to do the comparison.
-
 **assertJSONExact($test)**
 
 Similar to **assertJSONFragment()**, but checks the entire JSON response to ensure exact matches.