Default Roles in keystone: wrong format in example

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

- [x] This doc is inaccurate in this way: ______
- [ ] This is a doc addition request.
- [x] I have a fix to the document that I can paste below including example: input and output.

```yaml
"identity:create_foo": "role:service" or "role:admin"
```

has to be

```yaml
"identity:create_foo": "role:service or role:admin"
```

-----------------------------------
Release: 25.1.0.dev52 on 2022-11-02 15:54:51
SHA: a0cc504543e639c90212d69f3bcf91665648e71a
Source: https://opendev.org/openstack/keystone/src/doc/source/admin/service-api-protection.rst
URL: https://docs.openstack.org/keystone/latest/admin/service-api-protection.html