Docs 0.10: How to update symfony

Author: renatomefi

UPGRADE-0.10.md

@@ -3,11 +3,22 @@ UPGRADE FROM 0.9 to 0.10
 
 # Table of Contents
 
+- [Symfony]($symfony)
 - [GraphiQL](#graphiql)
 
+### Symfony
+ 
+ * Minimal supported Symfony version is now `^3.1 || ^4.0` 
+   
+   We've dropped support for Symfony 2.8 and 3.0
+   
+  Upgrading your Symfony version:
+   - [Upgrading to Symfony 3.0](https://github.com/symfony/symfony/blob/master/UPGRADE-3.0.md)
+   - [Upgrading to Symfony 3.1](https://github.com/symfony/symfony/blob/master/UPGRADE-3.1.md)
+
 ### GraphiQL
 
- * The GraphiQL class has been removed in favor of a new bundle.
+ * The GraphiQL interface has been removed in favor of a new bundle.
 
   Upgrading:
    - Remove the graphiql route from your application