Fix tty-pie github and rubydocs URL on README.md

[bandithijo]

Describe the change

What does this Pull Request do? => Just fix the GitHub & Rubydoc URL of tty-pie on README.md

Requirements

• [ ] Tests written & passing locally?
• [ ] Code style checked?
• [ ] Rebased with master branch?
• [x] Documentation updated?
• [ ] Changelog updated?