Create BMI_Calculator.java

[minhaj-313]

Description

Related Issue

This PR closes #

Motivation and Context

Screenshots (if any)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.

[SVijayB]

LGTM! Merging 🚀

[minhaj-313]

LGTM! Merging 🚀

Please labeled it as hacktoberfest-accepted