We should document how to use generic properties in the application.yaml file for the process engine configuration.

AT:

• Add a section in the docs how to use generic properties

  camunda:
    bpm:
      generic-properties:
        properties:
          enable-password-policy: true
  

• add a note that generic properties can be used for all engine configurations except for the already exposed ones (described in the camunda-engine-properties docs)
• add a note that setting generic properties that can be set via exposed properties have no effect