Merge branch '3.4' into 4.2

* 3.4:
  Update the PHP requirements for Symfony 3.4 version

Author: javiereguiluz

reference/requirements.rst

@@ -41,7 +41,7 @@ Run this command to install the tool:
     $ composer require symfony/requirements-checker
 
 Beware that PHP may use different configurations for the command console and
-the web server, so you need to check requirements in both environments.
+the web server, so you need to check the requirements in both environments.
 
 Checking Requirements for the Web Server
 ----------------------------------------