Improve "Other config options" page

I have just spent hours to figure out how to change the ``go-server``'s port. (Environment: Linux)

The official doc [here](https://docs.gocd.org/current/advanced_usage/other_config_options.html) does not provide enough information.

Workaround:

Adding ``wrapper.java.additional.{}`` property to ``/usr/share/go-server/wrapper-config/wrapper.conf``

For example,

```
wrapper.java.additional.12=-Dcruise.server.port=28153
```