minor #13007 Remove old versionadded (Nyholm)

This PR was submitted for the master branch but it was merged into the 5.0 branch instead (closes #13007).

Discussion
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Remove old versionadded

Build failed in #13006 because of these.

They are unrelated and I assume they should be removed.

Commits
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ff2b2fc Remove old versionadded

Author: OskarStark

configuration.rst

@@ -644,10 +644,6 @@ their values by running:
     # run this command to show all the details for a specific env var:
     $ php bin/console debug:container --env-var=FOO
 
-.. versionadded:: 4.3
-
-    The option to debug environment variables was introduced in Symfony 4.3.
-
 .. _configuration-accessing-parameters:
 
 Accessing Configuration Parameters

configuration/secrets.rst

@@ -4,10 +4,6 @@
 How to Keep Sensitive Information Secret
 ========================================
 
-.. versionadded:: 4.4
-
-    The Secrets management was introduced in Symfony 4.4.
-
 :ref:`Environment variables <config-env-vars>` are the best way to store configuration
 that depends on where the application is run - for example, some API key that
 might be set to one value while developing locally and another value on production.