plugins: mention static analysis support (#10812)

composer.json

@@ -63,6 +63,11 @@
     "extra": {
         "branch-alias": {
             "dev-main": "2.3-dev"
+        },
+        "phpstan": {
+            "includes": [
+                "phpstan/rules.neon"
+            ]
         }
     },
     "autoload": {

doc/articles/plugins.md

@@ -339,6 +339,25 @@ depend on other packages can function correctly, a runtime autoloader is created
 a plugin is loaded. That autoloader is only configured to load with the plugin dependencies,
 so you may not have access to all the packages which are installed.
 
+## Static Analysis support
+
+As of Composer 2.3.7 we ship a `phpstan/rules.neon` PHPStan config file, which provides additional error checking when working on Composer plugins.
+
+### Usage with [PHPStan Extension Installer][13]
+
+The necessary configuration files are automatically loaded, in case your plugin projects declares a dependency to `phpstan/extension-installer`.
+
+### Alternative manual installation
+
+To make use of it, your Composer plugin project needs a [PHPStan config file][12], which includes the `phpstan/rules.neon` file:
+
+```
+includes:
+	- vendor/composer/composer/phpstan/rules.neon
+
+// your remaining config..
+```
+
 [1]: ../04-schema.md#type
 [2]: ../04-schema.md#extra
 [3]: https://github.com/composer/composer/blob/main/src/Composer/Plugin/PluginInterface.php
@@ -350,3 +369,5 @@ so you may not have access to all the packages which are installed.
 [9]: https://github.com/composer/composer/blob/main/src/Composer/Plugin/Capability/CommandProvider.php
 [10]: https://symfony.com/doc/current/components/console.html
 [11]: https://github.com/composer/composer/blob/main/src/Composer/Util/SyncHelper.php
+[12]: https://phpstan.org/config-reference#multiple-files
+[13]: https://github.com/phpstan/extension-installer#usage