Add clear description of resolve env processor

Add a clear description of `resolve`  env processor, describing what is actually  resolved.

#13205

Author: wtorsi

configuration/env_var_processors.rst

@@ -232,8 +232,8 @@ Symfony provides the following env var processors:
             ]);
 
 ``env(resolve:FOO)``
-    Replaces the string ``FOO`` by the value of a config parameter with the
-    same name:
+    Replace all matches of ``%param_name%`` in the parameter ``FOO`` by the values of a config parameters with the
+    matched ``param_name``:
 
     .. configuration-block::