When selecting Vault as a service, generated config file fails validation

[gilzow]

If you select Vault duing the {paas} ify process, the generated configuration file fails validation (during push) with the message:

  E: Error parsing configuration files:
      - services: Uncaught exception: Vault service requires explicit endpoint configuration.
          at <script>:2:4
                throw(

My guess is that it is difficult, if not impossible, to know what a user needs for keys and types in their endpoint configuration, but we should then warn them that because they've selected Vault as a service they'll be required to add the endpoint configuration and then link to the docs.