docs: Improve low diskspace warning (#1158)

      GB=$(formatBytes "$FREE")

      LEFT=$(formatBytes "$LEFT")

      CUR_SIZE=$(formatBytes "$CUR_SIZE")

      msg="the virtual size of the ${DISK_DESC,,} is $CUR_SIZE"

      msg="The virtual size of the ${DISK_DESC,,} is $CUR_SIZE"

      if [[ "$USED" == "0" ]]; then

        msg+=","

      else

      if [ -n "$USED" ] && [[ "$USED" != "0" ]]; then

        USED=$(formatBytes "$USED")

        msg+=" (of which $USED is used),"

        msg+=" (of which $USED is used)"

      fi

      warn "$msg but there is only $GB of free space left in $DIR, make at least $LEFT more room available!"

      info "$msg, but there is only $GB of free space remaining in $DIR now."

      info "Please consider making at least $LEFT more space available in $DIR for future expansions."

    fi