[symfony/contracts] Reference one main CHANGELOG in each contracts

Author: nicolas-grekas

CHANGELOG.md

@@ -1,15 +1,5 @@
 CHANGELOG
 =========
 
-1.1.0
------
-
- * added `ServiceProviderInterface` in namespace `Service`
-
-1.0.0
------
-
- * added `Service\ResetInterface` to provide a way to reset an object to its initial state
- * added `Service\ServiceSubscriberInterface` to declare the dependencies of a class that consumes a service locator
- * added `Service\ServiceSubscriberTrait` to implement `Service\ServiceSubscriberInterface` using methods' return types
- * added `Service\ServiceLocatorTrait` to help implement PSR-11 service locators
+The changelog is maintained for all Symfony contracts at the following URL:
+https://github.com/symfony/contracts/blob/master/CHANGELOG.md