Added Rainwater Harvesting Calculator

[RajKhanke]

Fixes Issue🛠️

Closes #1335

Description👨‍💻

The Rainwater Harvesting Calculator is a web based application based on HTML CSS and JS that calculates the average annual rainwater that the harvesting tank can store (in liters) based on inputs fields such as:-

• height of the roof (in meters)

• width of the roof (in meters)

• Average annual rainfall (in mm) in the region

• Harvesting system efficiency (high, low, medium)

• Storage capacity of tank (in liters).

• The working is based on below formulas :-

    1) area = length * width
    2) total Rainwater = area * (rainfall / 1000) * efficiency * 1000

Type of Change📄

• [x] New feature (non-breaking change which adds functionality)

Checklist✅

• [x] I am an Open Source contributor
• [x] I have performed a self-review of my code
• [x] My code follows the style guidelines of this project
• [x] I have commented on my code, particularly in hard-to-understand areas

Screenshots/GIF📷

[netlify[bot]]

✅ Deploy Preview for calcdiverse ready!

Name	Link
🔨 Latest commit	fe20c268b6d896121f48242c2344fb0752883dc4
🔍 Latest deploy log	https://app.netlify.com/sites/calcdiverse/deploys/6679cd093fa032000842766e
😎 Deploy Preview	https://deploy-preview-1413--calcdiverse.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[RajKhanke]

@Rakesh9100 @Nihal4777 @jessicachawla i have updated index.html , please merge this pr along with gssoc'24 label and level

[Rakesh9100]

If any changes are suggested to do, then make the changes in the same opened PR by making the new commits. Don't create a new PR for that from the next time @RajKhanke

[github-actions[bot]]

Congrats, Your pull request has been successfully merged 🥳🎉 Thank you for your contribution to my project 🚀 Keep Contributing!! ✨ @RajKhanke