Fix for (obvious) issue when using firewall (e.g. ufw)

[JanLalic]

Dear Creator

first of all, thanks for this great module!
After installing I had some issues because of the firewall (at that time I hadn't thought about it).
It'd be great if one could add a remark in the README that it's necessary to allow connections to and from the phones IP adress.
Though it is somewhat obvious, there might be some people who don't think about it in the first moment.

For me the following rules for ufw worked great (though there are certainly better ways to do it):
sudo ufw allow from IPOfTheDevice to IPOfThePi port ThePortThatIsUsed
sudo ufw allow from IPOfTheDevice port ThePortThatIsUsed

(I needed both for the needed IPs - am not sure why since outgoing connections should be allowed by default anyway ...)

One could add as well a range of IPs - then the IPOfTheDevice would be something like 192.168.0.0/24. (You know that obviously but the readers might not ;))

Cheers and thanks again!

[kevinatown]

@confused-lynx thanks for this! Def. a good idea I'll see if i can have sometime to add this to the readme, I def dont mind if people put in PRs of improvements :)

Thanks again!