Uploaded Navbar with Dark mode switch

[mahesh-143]

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Description 📜

Added Responsive navbar with burger menu and dark mode switch Fixes #44

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This would be great if you provide any of this 📝

• [ ] Video (Animations, screen-recordings, presentations and regular explanatory films are all possibilties etc)
• [ ] Documentation (Content Creation in the form of codes or tutorials)
• [ ] Other (If you choose other, Please mention changes below)

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Domain of Contribution 📊

• [x] Navbar design
• [ ] Footer
• [ ] Single page website
• [ ] Animation design
• [ ] parallax effect design
• [ ] Others

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Checklist ✅

] - [x] I have performed a self-review of my own code or work. - [x] I have commented my code, particularly in hard-to-understand areas. - [x] My changes generates no new warnings. - [x] I'm **Hacktoberfest** contributor

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## Any tutorials or documentation have you added (made by you only not from google) - [ ] Tutorial - [ ] Documentation

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## Screenshots / Gif (Compulsory) 📸

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[mahesh-143]

Requesting review @Ayan-thecodeking