Installation instructions

Author: ondrejmirtes

README.md

@@ -4,17 +4,24 @@
 [![Latest Stable Version](https://poser.pugx.org/phpstan/phpstan-deprecation-rules/v/stable)](https://packagist.org/packages/phpstan/phpstan-deprecation-rules)
 [![License](https://poser.pugx.org/phpstan/phpstan-deprecation-rules/license)](https://packagist.org/packages/phpstan/phpstan-deprecation-rules)
 
-## Usage
 
-To use these rules, require it in [Composer](https://getcomposer.org/):
+## Installation
+
+To use this extension, require it in [Composer](https://getcomposer.org/):
 
 ```
 composer require --dev phpstan/phpstan-deprecation-rules
 ```
 
-And include rules.neon in your project's PHPStan config:
+If you also install [phpstan/extension-installer](https://github.com/phpstan/extension-installer) then you're all set!
+
+<details>
+  <summary>Manual installation</summary>
+
+If you don't want to use `phpstan/extension-installer`, include rules.neon in your project's PHPStan config:
 
 ```
 includes:
-	- vendor/phpstan/phpstan-deprecation-rules/rules.neon
+    - vendor/phpstan/phpstan-deprecation-rules/rules.neon
 ```
+</details>