fix-disk-alert-script

[vishnubish1255]

Which Issue Does This Fix?

Closes # (4)

Steps Taken To Fix It

Please briefly explain what code you added to the script to solve the # TODO:.
"i extracted the disk usage then compared it to threshold"

(e.g., "I added color 3 33 for the 'yellow' key inside the associative array.")

Testing

Did you test your script locally according to the README.md instructions?

• Yes! The script runs without errors and performs the expected action.

General Checklist

• I have followed the instructions in CONTRIBUTING.md.
• The name of the PR explains what I changed.