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📷

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[RajKhanke]

@Rakesh9100 @jessicachawla please merge this pr which will resolve issue 1335 , along with Gssoc 2024 label and level. I'm a contributor in Gssoc'24

[Nihal4777]

@RajKhanke Add your calculator in main index page.

[RajKhanke]

@Nihal4777 okay i will close this Pr and make changes in new PR