Update readme

README.md

@@ -4,7 +4,7 @@
 
 # swagger-php
 
-Generate interactive [OpenAPI](https://www.openapis.org) documentation for your RESTful API using [doctrine annotations](https://www.doctrine-project.org/projects/doctrine-annotations/en/latest/index.html).
+Generate interactive [OpenAPI](https://www.openapis.org) documentation for your RESTful API using [doctrine annotations](https://www.doctrine-project.org/projects/doctrine-annotations/en/latest/index.html) (optional as of version 4.8) or PHP attributes.
 
 For a full list of supported annotations, please have look at the [`OpenApi\Annotations` namespace](src/Annotations) or the [documentation website](https://zircote.github.io/swagger-php/guide/annotations.html).
 
@@ -41,6 +41,16 @@ For cli usage from anywhere install swagger-php globally and make sure to place
 composer global require zircote/swagger-php
 ```
 
+### doctrine/annotations
+As of version `4.8` the [doctrine annotations](https://www.doctrine-project.org/projects/doctrine-annotations/en/latest/index.html) library **is optional** and **no longer installed by default**.
+
+If your code uses PHPDoc annotations you will need to install this as well:
+
+```shell
+composer require doctrine/annotations
+```
+
+
 ## Usage
 
 Add annotations to your php files.