Added currency exchange rates script

[altirel]

Description

Added a script that can convert your choosen currency amount to another choosen one with current exchange rates.

Fixes #92

Look at description.

Have you read the Contributing Guidelines on Pull Requests?

• Yes
• No

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines(Clean Code) of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have created a helpful and easy to understand README.md
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests/screenshots(if any) that prove my fix is effective or that my feature works.

[avinashkranjan]

LGTM..🚀

[avinashkranjan]

@all-contributors please add @xayke for code

[allcontributors]

@avinashkranjan

I've put up a pull request to add @xayke! 🎉