added solution for directories_comparision.md

[Prajwalmithun]

Hi @bregman-arie,
I have added the solution for this issue #240
Please check and accept my PR

Thanks,
Prajwal

[Prajwalmithun]

I was checking the other PRs for this question. I guess you asked for a solution that displays a message if both the directories are the same. I have added those features as well in the below script. Please check

#!/bin/bash

if test $# -ne 2
then
	echo -e "USAGE: ./dirdiff.sh directory1 directory2"
	exit 1
fi

# check for the checksums. 
# If both the checksums same, then both directories are same
if test `ls -1 $1 | sort | md5sum | awk -F "  " '{print $1}'` == `ls -1 $2 | sort | md5sum | awk -F "  " '{print $1}'`
then
	echo -e "No difference between the 2 directories"
	exit 0
fi

diff -q $1 $2

[bregman-arie]

Looks good. Thank you