Add link to Running Kolibri on a different port when the default port is in use

[SavvyOsive]

For someone initially setting up Kolibri, getting the default port 8080 already in use is a common issue, it will be better if a note is provided to the end users in advance with the reference to the doc for running Kolibri on a different port.

[SavvyOsive]

@indirectlylit please check

[radinamatic]

@SavvyOsive Thank you for suggesting this improvement, and including the change by @indirectlylit. To make the link more accessible, please do not wrap one word only inside, but extend it a bit more:

 .. note::
   By default **Kolibri** starts on 8080 port. If the default port is in use, refer to these :ref:`steps to change the port <different_port>`.

[SavvyOsive]

@radinamatic @indirectlylit Please review now, thanks.