Do not include overlay in diskstats

Fixes #11

35-diskspace

@@ -11,7 +11,7 @@ dim="\e[2m"
 undim="\e[0m"
 
 # disk usage: ignore zfs, squashfs & tmpfs
-mapfile -t dfs < <(df -H -x zfs -x squashfs -x tmpfs -x devtmpfs --output=target,pcent,size | tail -n+2)
+mapfile -t dfs < <(df -H -x zfs -x squashfs -x tmpfs -x devtmpfs -x overlay --output=target,pcent,size | tail -n+2)
 printf "\ndisk usage:\n"
 
 for line in "${dfs[@]}"; do