Reword versionadded sentences to be consistent

Author: OskarStark

configuration/micro_kernel_trait.rst

@@ -203,8 +203,8 @@ hold the kernel. Now it looks like this::
 
 .. versionadded:: 3.4
 
-    Support for annotation routing without an external bundle was added in
-    Symfony 3.4. Prior to version 3.4, you needed to install the
+    Support for annotation routing without an external bundle was introduced
+    in Symfony 3.4. Prior to version 3.4, you needed to install the
     SensioFrameworkExtraBundle.
 
 Unlike the previous kernel, this loads an external ``app/config/config.yml`` file,

service_container.rst

@@ -512,7 +512,7 @@ pass here. No problem! In your configuration, you can explicitly set this argume
 
 .. versionadded:: 3.3
 
-    The ability to configure an argument by its name (``$adminEmail``) was added
+    The ability to configure an argument by its name (``$adminEmail``) was introduced
     in Symfony 3.3. Previously, you could configure it only by its index (``2`` in
     this case) or by using empty quotes for the other arguments.