minor #7211 [PHPUnitBridge] Fix versionadded notes (Jean85)

This PR was submitted for the master branch but it was merged into the 3.1 branch instead (closes #7211).

Discussion
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[PHPUnitBridge] Fix versionadded notes

I was reading the docs and noted that those features were marked as present only from Symfony 3.1/2. The reality is that the version that includes that stuff is the bridge's, which is backward compatible!
So, as an example, I can use the bridge v3.2 on my Symfony 2.8 app.

I think it should be helpfull to specify that more clearly.

Commits
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59e3f95 [PHPUnitBridge] Fix versionadded notes

Author: xabbuh

components/phpunit_bridge.rst

@@ -122,8 +122,8 @@ Disabling the Deprecation Helper
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. versionadded:: 3.1
-    The ability to disable the deprecation helper was introduced in Symfony
-    3.1.
+    The ability to disable the deprecation helper was introduced in the 3.1 
+    version of this component.
 
 Set the ``SYMFONY_DEPRECATIONS_HELPER`` environment variable to ``disabled`` to
 completely disable the deprecation helper. This is useful to make use of the
@@ -215,7 +215,8 @@ DNS-sensitive Tests
 -------------------
 
 .. versionadded:: 3.1
-    The mocks for DNS related functions were introduced in Symfony 3.1.
+    The ability to disable the deprecation helper was introduced in the 3.1 
+    version of this component.
 
 Tests that make network connections, for example to check the validity of a DNS
 record, can be slow to execute and unreliable due to the conditions of the