Added Bengali Translation for README.

[x3shat]

🤔 This is a

• [ ] Feature
• [ ] Bug
• [ ] Documentation Update
• [x] Translation

✍ Description

• Write a short description Completed Bengali translation of readme file

Added to documentation

• [x] readme file
• [ ] No documentation needed

🐱‍💻 Use a meme/gif to describe how you feel for contributing (optional)

[muchirijane]

@x3shat, go through the Contribution md file first. Then create another pull request.