health-check.sh: filter Docker overlay mounts from disk space check

health-check.sh

@@ -61,7 +61,7 @@ check_disk() {
         else
             ok "Disk usage at ${pct}% on $mount"
         fi
-    done < <(df -h | awk 'NR>1 && $6 !~ /^(\/dev|\/sys|\/proc|\/run|\/snap)/ {print}')
+    done < <(df -h | awk 'NR>1' | grep -v ' /dev' | grep -v ' /sys' | grep -v ' /proc' | grep -v ' /run' | grep -v ' /snap')
 }
 
 check_common() {