Make/Update guide for server owners to enable SLAM for TF2 servers

[FaxMac]

The FAQ says the following

To play a track in a CS:S or TF2 server, the server must have "sv_allow_voice_from_file" set to "1" and "sv_use_steam_voice" set to "0".

However, the sv_use_steam_voice seems to be deprecated and replaced by sv_voicecodec according to Valve

https://developer.valvesoftware.com/wiki/List_of_TF2_console_commands_and_variables

That's why I was wondering if they could update the guide to properly set up a TF2 server to use SLAM

[FaxMac]

I seems to enable SLAM in my server, these 2 convars should be enabled on server.cfg

sv_use_steam_voice 0 sv_voicecodec vaudio_celt_high