Adding sound support via soundcmd in config.h

[Binkersss]

Sound is enabled by switching the populating the soundcmd array.

Example:

static const char *soundcmd[] = { "pw-play", "/path/to/sound/file", NULL };

Sound support is disabled by support. This is from a personal patch I've been using for a little bit and has saved me from letting my laptop die a ton. Without the sound, I will never notice it.

[Binkersss]

Sorry, I've just realized you may prefer this to be a patch. Let me know and I can change the formatting of this pr. Honestly I feel like sound is becoming a basic function of a notification, and this addition is only 17 lines so I thought it was acceptable to create a basic PR.