Update README.md

Author: staabm

README.md

@@ -31,7 +31,7 @@ are however several advantages to using this library:
 In order to inspect a codebase you need to tell composer to include the `phpdocumentor/reflection` package. This
 can easily be done using the following command in your command line terminal:
 
-    composer require "phpdocumentor/reflection: ~3.0"
+    composer require "phpdocumentor/reflection: ~4.0"
 
 After the installation is complete no further configuration is necessary and you can immediately start using it.