Readme: suggest reportAnyTypeWideningInVarTag along enforceListReturn (…

…#226)

README.md

@@ -298,6 +298,7 @@ iterator_to_array($fn()); // denied, would fail
 - Enforces usage of `list<T>` when list is always returned from a class method or function
 - When only single return with empty array is present in the method, it is not considered as list
 - Does nothing when [list types](https://phpstan.org/blog/phpstan-1-9-0-with-phpdoc-asserts-list-type#list-type) are disabled in PHPStan
+- Consider enabling also [reportAnyTypeWideningInVarTag](https://phpstan.org/config-reference#reportanytypewideninginvartag) in native PHPStan as it mostly affects lists
 ```php
 /**
  * @return array<string>