made simple calculator project

Hello, I added a simple calculator project using HTML, CSS, and JavaScript for the Collection repository.

[x] Have you checked that there aren't other projects for the same topic in any language?
[x] Does your project contains a README and REQUIREMENTS file to help a newbie understand and execute your project code?
[x] Have you tested your code locally within another machine for it to execute without changes/updates?
[x] Does your code conform to the hacktoberfest rules?
[x] Do you accept that this code is not available elsewhere on internet and you completely owe the rights to this project code.

OyePradumya / Collection