Add a dark mode toggle for the website

[ywalia01]

Is your feature request related to a problem? Please describe.
An anchor link to toggle between dark/light mode on the website

Describe alternatives you've considered
Darkmode-js package can also be implemented but I found it inadequate when I used it on one of my projects

Additional context
Refer to this article - https://aqeel.cc/2018/09/25/dark-reader-theme-on-your-website/#:~:text=Install%20Dark%20Reader%20Browse%20to,unfold%20the%20tag.
for help.
Here's the link to darkmode-js package - https://darkmodejs.learn.uno/

[shweta-laha]

Hey! I would like to contribute if you want

[tushar5526]

@shweta-laha go ahead!