Many errors on the Introduction

[dmvianna]

I think the introduction has many obvious errors, and I stopped reading there. Sorry for not being very specific, but you need to review it. One example:

function getFirstLetter(str: string): string {
  return universe.name.substring(0, 1);
}

console.log(getFirstLetter("functional programming")); // 'f'

Where are you using the str parameter in this function?

Thank you for creating a public resource for people wanting to learn fp-ts. Please review it though.