[BUG][scala-akka] generates a readme linking to model docs that don't exist

Created by: ckipp01

Bug Report Checklist

Have you provided a full/minimal spec to reproduce the issue?
Have you validated the input using an OpenAPI validator (example)?
Have you tested with the latest master to confirm the issue still exists?
Have you searched for related issues/PRs?
What's the actual output vs expected output?
[Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

While using scala-akka generator it seems impossible to get the model docs generated. For example, I followed the instructions similar to those in the WIKI to test this against the current master branch:

git clone https://github.com/openapitools/openapi-generator.git
cd openapi-generator
mvn clean install
java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate \
  -i modules/openapi-generator/src/test/resources/3_0/scala-akka/petstore.yaml \
  -o scala-test
  -g scala-akka

After doing this you'll see that there is a README.md created that has the following section:

## Documentation for Models

 - [ApiResponse](ApiResponse.md)
 - [Category](Category.md)
 - [Order](Order.md)
 - [Pet](Pet.md)
 - [Tag](Tag.md)
 - [User](User.md)

However, none of these model docs actually exist.

openapi-generator version

The last commit at the time of checking this is https://github.com/OpenAPITools/openapi-generator/commit/158649aff9a87b13b448880d7ca6a4ac35fadcc2

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/test/resources/3_0/scala-akka/petstore.yaml

Generation Details

Just follow the steps up above in the description

Steps to reproduce

Just follow the steps up above in the description

Related issues/PRs

Not exactly sure if these are the same or related, but they all seems to have to do with scala-akka and doc generation not working as expected.

https://github.com/OpenAPITools/openapi-generator/issues/8966 https://github.com/OpenAPITools/openapi-generator/issues/5795

Suggest a fix

I'm pretty unfamiliar with how this is all supposed to work, so no idea.