Updated references to new Session()

If you use new Session(), you get a 500 error, with the following message:

```log
Failed to start the session: already started by PHP.
```

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | I tested 2.4.2, but it most likely will be earlier version as well
| Fixed tickets | none