Symfony version(s) affected: 4.1.5

Description
The workflows configuration does not work as documented by condole config:dump-reference or console debug:config. The following configuration should be valid:

framework:
  workflows:
    enabled: true # explicitly enable workflows
    workflows:
      my_workflow:
        # ... workflow configuration

However, this configuration leads to the following error:

Unrecognized option "my_workflow" under "framework.workflows.workflows.workflows"

How to reproduce

Use the configuration above on a clean Symfony, then clear the cache.

Possible Solution
The bug seems to be caused in beforeNormalization() call for the workflow section (src/Bundle/FrameworkBundle/DependencyInjection/Configuration.php lines 218-236). When an enabled key is present, it deletes the key, then nests the rest of the configuration in an additional workflows key. This causes the workflows of the example config above to become invalid:

framework:
  workflows:
    enabled: true
    workflows:
      workflows:
        my_workflow:
          # ... workflow configuration