Add port 32500/tcp to support article

[mongerj]

I would recommend adding port 32500/tcp to the list below for Plexamp remote control. I was trying to get it working across a firewall, and had to comb through a list of all listening ports to find it.

https://support.plex.tv/articles/201543147-what-network-ports-do-i-need-to-allow-through-my-firewall/