Create Count of Smaller Numbers After Self

[Piyush6869]

Title of the problem

Checklist before requesting a review

• I have checked the guide for contributions.
• I have added the description at the top of the solution file.
• I have added a test file for the problem.
• I have added an entry to the README file with a link to the new file.
• I have run linter (npx eslint LeetcodeProblems LeetcodeProblemsTests) and unit tests (node Test.js) and they pass. More info.

Check the guide and this PR example.

[ignacio-chiazzo]

Hey! thanks for contributing.

Could you add:

• The problem at the top of the file (exapmle)
• A test file with a few scenarios (example)
• A link to this problem in the Readme like this

Thanks!

[ignacio-chiazzo]

This repository is only for Javascript at the moment. Could you rewrite the Python solution into JS?