Add websockify-audio and apache config to readme

[watercrossing]

Forwarding audio requires an additional websocket to be forwarded.
Since I use apache I thought I include my apache config.

[jlesage]

Could you provide more details about your apache config ? It seems that the websocket part is not working for me, I'm getting the error AH00898: Unexpected Upgrade: websocket (expecting n/a) returned by /websockify. So maybe there is a config element I'm missing that should also be documented.

[gwenl]

It seems it's the order of ProxyPass and ProxyPassReverse that are wrong. The least specific ones must be the last in the virtualhost configuration. So the directives that apply to root (/) must be placed after those that apply to /websockify and /websockify-audio.
Also, those apache modules are required: proxy, proxy_http, proxy_wstunnel.