Align PHP 8.4 QA config and docs

Author: ohmyfelix

README.md

@@ -39,7 +39,9 @@ https://examples.contributte.org/api-router-skeleton/
 
 ## Installation
 
-To install latest version of `contributte/api-router-skeleton` use [Composer](https://getcomposer.org).
+You will need `PHP 8.4+` and [Composer](https://getcomposer.org/).
+
+To install latest version of `contributte/api-router-skeleton` use Composer.
 
 ```
 composer create-project -s dev contributte/api-router-skeleton acme

phpstan.neon

@@ -3,6 +3,7 @@ includes:
 
 parameters:
 	level: 8
+	phpVersion: 80400
 
 	paths:
 		- app

ruleset.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <ruleset name="Contributte">
 	<!-- Extending rulesets -->
-	<rule ref="./vendor/contributte/qa/ruleset.xml"/>
+	<rule ref="./vendor/contributte/qa/ruleset-8.4.xml"/>
 
 	<!-- Specific rules -->
 	<rule ref="SlevomatCodingStandard.Files.TypeNameMatchesFileName">