waybar: add module for player metadata

config/.config/waybar/config

@@ -2,6 +2,7 @@
   "position": "top",
   "modules-left": [
     "sway/workspaces",
+    "custom/player",
     "sway/mode"
   ],
   "modules-right": [
@@ -21,6 +22,9 @@
     "format": "--{}--",
     "tooltip": false
   },
+  "custom/player": {
+    "exec": "playerctl metadata -f '{{title}}' -F"
+  },
   "pulseaudio": {
     "tooltip": false,
     "format-muted": "MUTE",