Update symfony supported versions in readme

Antoine Lelaisant · PedroTroller · commit ae4bd9efe922 · 2018-02-15T09:38:16.000+01:00
diff --git a/README.md b/README.md
@@ -6,7 +6,7 @@ DictionaryBundle
 Are you often tired to repeat static choices like gender or civility in your apps ?
 
 ## Requirements
-- Symfony >= 2.8
+- Symfony >= 3.0
 
 ## Installation
 Add the DictionaryBundle to your `composer.json`:
