remove explicit references to homedir path

dot_config/beets/config.yaml.tmpl

@@ -1,4 +1,4 @@
-directory: /home/joel/Music
+directory: ~/Music
 library: ~/.config/beets/library.db
 plugins: chroma embedart edit convert fetchart missing unimported
 
@@ -28,7 +28,7 @@ convert:
   embed: yes
   copy_album_art: no
   never_convert_lossy_files: yes
-  dest: /home/joel/Downloads
+  dest: ~/Downloads
 
 acoustid:
   apikey: JrQ02aAnhy