add interface when necessary (you can have a look at the typescript cheatsheet)

[flexbox]

This is nice 88d45f8 👏

But if we really want to have Typescript support to respect the first step of pyramid testing in JavaScript, we should add type-check

https://testingjavascript.com/

Example for single.tsx:

we can add

interface SingleProps {
  pageContext: any,   <--- this is not ideal but leave any for now :)
  title: string,
  twitterName?: string,
  location: string,
}

function singleQuote(props: SingleProps) {
  ...
}